Lessons from building Vercel v0 and the d0 agent - The Pragmatic Summit
836 segments
Malta, thanks for having the
conversation with us today.
Um,
this time it feels different when it
comes to coding agents. I think there
have been times in the past where, you
know, it it felt like it was uh a little
revolutionary, but I think this time
we're all trying to figure out how we
are supposed to build while the ground
underneath us is shifting. And so super
happy to be speaking with you today. I
think that with your products uh DZ your
internal data agent and then Verscell V0
as well your public facing thing um
you've
you've been able to roll with the
punches and and be able to build and and
create products as the world has changed
around us. Let's start with DZ your
internal uh data agent. What was your
first approach there and why did it turn
out to be so flawed?
>> Yeah, to give folks a little bit of
context like the thing that makes
Versell strong is that we always build
things with our own technology and like
one of our thesis is that like building
agents actually extremely easy and you
don't need to buy them. You can just
build them yourself. And so we build one
ourselves and so the the agent that we
call DZero internally is a is a text of
SQL engine. So you you give it any
question in Slack and it will reply with
the answer and it has access to our
entire snowflake kind of subject to the
to the access rules of the of the user.
Right? And so um I I'll share one query
which I think is the funniest one. It's
a salesperson. You'll hate it all. Um so
this early this year they um this person
asked the following question. uh which
S&P 500 CTOs and VPs of engineering have
private Versel accounts and have
deployed over Christmas.
So presumably they got like an email or
a call. I don't know. But like I think
like that's like if like actually
finding that from I mean obviously you
have to do a little bit of research. You
have to go to LinkedIn etc. The agent
does as well but then eventually you
kind of figure out the right snowflake
query. It's it's very very difficult
right? Um, and so the the initial
version of this agent was kind of this
kind of traditional infrastructure where
you have, you know, the agent is a tools
in a loop type of thing. Has all kinds
of different tools to do all kinds of
different things. Um, and it wasn't like
it was working badly, but it was, you
know, maybe not as magical. And then we
deleted everything and switched to like
an agent that looks very similar to a
coding agent. Now it's it's it's still
kind of custom coded like it doesn't use
for example cloud code as a harness uh
because again building such a harness is
actually really easy and you can just do
it. Um but otherwise it kind of looks
the same way. So the the the general
architecture is that we did the work of
going through our entire snowflake and
for every single column
in pros explaining the business value,
right? And that gets exported to a YAML
file. And the the agent
essentially gets told, you know, you got
post-trained on using GP on tail and and
all these things, right, that you need
for coding and go to go to town on these
YAML files to figure out the business
semantics of everything. And then you
make a SQL query. Um, for that it has a
completely different custom tool and
that's it. So there's just two tools.
There's the bash tool and there's the
SQL execute SQL tool. and and that's the
entire agent. So, it has like 50 lines
of code. Um and and it's completely
transformational for the business.
>> What led you to understand that you
needed to throw everything away? Cuz I
feel like you go and you build all of
this this code and it's it's just so
hard to light it on fire and then start
from from scratch again.
>> Yeah. I think like I think in the in the
world of agents, you have to be humble
in the sense of like we're just
discovering how to build them. And so
just because something was best practice
like in the summer of 2025 means quite
little today and like that's different
from like I don't know if you've built a
website you know it's been 30 years and
we kind of know how to do it but on you
know agents are in their maybe third
year for real if at all right um and so
you have to be willing to entertain the
notion that yeah maybe there's actually
now a better way to do it and like it's
kind of proportional to the models
getting more intelligent so you And it's
more viable now to have agents that are
essentially it's fully relying on the
emergent behavior and and respectively
um are more simple because you don't
have to prompt them so much. You don't
have to hard code so many rules.
>> Uh on the Verscell blog you had a uh a
post it was titled I think all you need
is the file system in bash. Is that is
something like that? And so you just
took a complete step backwards and and
described what the the data was in in
plain English and sort of like you just
step back and let it cook and and move
to a much more declarative model with
everything,
>> right? Yeah. The intuition is that you
kind of you have to think about like
what was the model trained on like what
what what is it optimized on? And for
now there's lots of coding tasks, right?
And it'll change in the future. And so
if you can make things look like like
they're a coding task even though
they're not um then you can uh you have
you get disproportional good results.
>> How many CEOs and CTOs in the the
Fortune 500 are using Versell on their
personal accounts?
>> I I don't have the precise number. It
was pretty substantial.
>> Okay.
>> Yeah.
>> Dozens of them.
Well, I just it is it's quite amazing
now to see all of these CEOs and CTO's
come out of the woodwork and start
coding and and doing all these agents.
Are are you one of those CTOs that are
close to the ground and and shipping
stuff?
>> I was already before, but I'm I'm deep
in 12 hours a day coding. And by coding,
I mean like I I can do meetings, right?
cuz I can, you know, just kind of every
so often uh optimize the I go in, check
the prompts, deliver a code review.
Yeah, I'm super back. Uh I I've been for
for the longest time kind of oscillating
between coding a lot and and not coding
so much and I'm I'm back on um like
24/7.
>> What's what's your drug of choice? Your
agent of choice.
>> So for I mean for Versell, we try for
folks to get a broad experience across
the company. We want to feel what our
users feel. So we want to we don't we
don't mandate anything. Um my current
stack but it's subject to change is uh
clot with 4.6 fast and then I'm using uh
codeex 5.3 for code reviews.
>> Yeah. Yeah. It's uh it's quite amazing.
It's just this like dopamine hit where
you're you're uh you're hitting the the
slot machine hoping that you get
something awesome out of it.
>> Right. Like that. By the way, I had u
there was an article in Wall Street
Journey journal of me basically saying
that and so that was my first ever quote
in a major newspaper. Here you go.
>> Oh okay.
>> Oh wow. We both came to that.
>> So voted to be addicted. But yeah I'm I
I maybe I'm not addicted but I do love
it. It's such a good experience.
>> Well let's shift to Verscell Vzero uh
which I think you launched back in 2023.
Is that correct? Yeah. So the original
pitch was um anybody should be able to
make an application even non-engineers
and you could do some prototyping and
stuff like that which was I think pretty
revolutionary at the time. What did you
think Vzero was going to be and how
quickly did it start diverging from the
plan?
>> Yeah, I think initially we we thought we
were building a tool for front-end
engineers uh because that's what we're
doing in general, right? And so like we
we thinking we were making a tool for
ourselves and
we then realized we actually built a
tool for backend engineers because it
was empowering them but it also sucked
um in the sense that it didn't work all
the time. And you know this is 2023 GPD
3.5 GPD4 days and so it didn't work all
the time but the back end engineers they
were good enough to fix it in the cases
where it didn't work but you couldn't
have given it to a non-engineer at the
time right because it was just not um
reliable enough and and so that was the
that was the kind of the main part of
market fit for a while and then uh we
but again in the AI space you have to be
humble right like you have to be willing
to entertain that the world is changing
around you so sometimes people call it a
pivot but it's It's not really the right
word because usually that's used for the
cases where you realize that you kind of
made a mistake on your internal data and
you have to do something else. Whereas
let's say anthropic ships sonnet 3.5 and
suddenly essentially the same prompt can
be used to build full stack apps which
previously just wasn't possible. You
cannot now keep your product the same
because the world is different, right?
Um and so that that was like a major
milestone where like we we realized okay
we have to um and I mean obviously this
amazing right like we can we can now h
uh adopt our product to be able to build
like end to-end applications and also
with a success rate that kind of
approach is the the case where um where
a non-engineer can be successful.
So you told me there were about five oh
moments when it came to vzero um over
the years where the models took a really
big step forward or you know usage
patterns shifted and you needed to
rethink things. Can you take us through
one of one or two of those moments and
and how you were sort of thinking about
things? Yeah, I mean definitely the
first one was um like in the summer of
2023 when um to take us all back, right?
The CHBT had launched and LMS were still
kind of new and and and broad adoption
and
these things were making text and so I
think us and everyone was thinking like
we got to like it must be possible to
make web pages with these things and
back in the day when you tried you would
realize that it wouldn't do a good job.
uh like it would kind of do it but like
it wouldn't look good. It would kind of
be be um be subpar. Not something you
would package as a product. And I still
remember to this day sitting at the like
we had like someone actually who who is
from China and lives in Berlin, but he
was in our office in San Francisco and
he was hacking away and then at some
point he was like raising his hand like
guys I've I found something. And so he
had just changed the prompt to say use
Tailwind.
And this was such a like serendipity
moment because Tailwind at the time
which is it's like a way to write CSS um
at the time it was old enough that it
was in the CHBT 3.5 um training kickoff.
Um but at the I mean at that time it
wasn't super popular yet but it was
enough training data and so the model is
so much better at doing inline reasoning
rather than saying we have to write a
CSS file then later write CS HTML. the
models at the time were too dumb to do
that. So they so they couldn't, right?
But if you if you told them basically
just put everything in the same place,
then they did a real job. And so that's
kind of how we figure out how to build a
product that actually was viable back in
the day, right? Um so that that was the
kind of the first milestone to actually
make it work. Um eventually like I mean
I already mentioned that we like the
second really big pivot was was that um
I think the the the final step you know
obviously there was like this whole
ecosystem now of of products kind of in
this space and and some of them went
very much like into the consumer space
um and and we definitely discovered okay
there's this like enterprise use case so
like when for vzero the the users we're
aiming for I would call tech adjacent
right so it's the it's the PM, it's the
designer, it's the the product owner,
the the business person who's kind of
interested. It's like um that found the
law of product market fit. Um and then
the final use case, and I'd love to talk
a little bit more about that, but like
that is essentially um I'm a I'm a
business person at a company. I'm going
to make an internal app for myself,
right? um kind of the new like crazy
onslaught of of shadow IT um is
definitely something that that we're
very interested in both from a from a
from the VCR point of view but also from
the Versel deployment point of view.
How do you think about
um how do you think about the fact that
the models are so fully capable right
now and like where does Verscell sit in
uh as a product, you know, as these
models get better and better?
>> Yeah. So, we're we're a multi-product
company, but like so our core business
for folks who don't know is you throw
over the fence and we're going to
run it for you. Um, and the the beauty
of that is that there's no more being
made right now. Sorry for cursing on TV,
but here we go. Um, so like like like
every like we love it if you use cloud
code, if you use cursor, you know, like
if at some point you're going to have to
have a place to run it and and um you
know, we can connect Versell to your git
repository and every time you push um
we'll make you uh a new version of it
and have it in production. So, so that's
kind of like that's how I see my primary
position in that marketplace, right? And
then, you know, with VZero, for example,
obviously you're also playing kind of on
the creation side, but I certainly spend
most of my time actually on the the
question of how do I run these apps that
are made in a different way in
production in a way that's um like
that's appropriate for this new type of
application.
So on a scale of 1 to 10, as the CTO of
a tech company in 2026, how worried are
you that the stuff that you've built
will become obsolete as these models get
better and better?
There's things I'm worried about. Um,
but I don't really see like uh like
again like you know since we're in the
business of operating software um I
don't see a major disruption there. Like
you could argue, you know, the agents
are also great at writing Terraform,
like you know, they can just make the
infrastructure for you, but like that's
actually not how that works, right? like
the the the whole idea of of of any form
of professional DevOps is that I have
like somewhat an idea of what's going on
and and so I can't like you can't really
vibe code that like you you so you there
has to be there always has to be some
form of platformization of how I run
something
>> and um and so that like you know
essentially we're playing in that in
that space relatively successfully. So
for that from that point of view I'm
actually not particularly worried. Well,
do you think that the lack of
observability is a temporary limitation
or a fundamental limitation of
long-running agents?
>> Like uh you know I think that the the
there's there's a whole you know there's
a whole revolution ahead of us of of
agents participating further in in kind
of the DevOps space and and and and
running your application. um we started
calling it kind of self-driving
um like infrastructure where like where
the you know where you have essentially
something that in an agentic way kind of
understands what's going on. Um but yeah
I think that still kind of like relies
on the fact that there is a certain
uniformity how how things are running
versus essentially you know let letting
the AI kind of loose.
If you were to start the Vzero team
today from zero, how would you do it
differently than when you started it in
23?
>> Oh, that's a really good question. I I
think the the obviously now we under
like if you already know what what the
product market fit is, you can jump over
all these steps, right? Um I think the
the big difference is that today you
actually don't need a team. Like so if
you start why would you have a team?
Teams just I don't know make things go
slower, right? Like you can you can
always go to the step where like where
you where you have enough that you can
make a judgment call as to what whether
that's worth investing with a single
person. And maybe there's two of them.
Maybe there's three of them, right? But
it's not like seven people, right? And
so I would I would tell someone, "Go
figure out what the product is and give
me a demo and if the demo is good, I'm
going to give you a team."
>> So you would just have one dude like
just go and do it after you found the
market fit
>> or Gallop. But yeah.
>> Yeah. Yeah. Yeah. That's amazing. Um so
how are you thinking about your dev
teams within Versel then? Are they much
more about like one person and and one
sphere of ownership and then they go and
they do everything or are you trying to
retrofit maybe like a broader team
dynamic?
I don't I definitely don't think we have
like in a major way kind of changed how
how how we operate. Um, I think it was
always a good idea to have individuals
to be able to ship something end to end
and and to not really always rely on the
entire operation to make progress. And I
think that's kind of like many of these
many of these things, you know, continue
to be true, but they're they're probably
more painful now if you if uh if you if
you you know increase the speed of the
inner loop through a coding, but your
outer loop of shipping is uh is
different. Um I give you one example
which I think is relevant for this
group. Um so I I was at Google before
for 12 years. I led like part of the
search team. Um you can imagine
essentially being a very slow oper
operation, right? Uh my job was
essentially to approve things via email
and go to meetings. Um and so I didn't
want to build the organization. And so
the the the pattern that we use at
Verscell is what in the nerdiest way you
could describe as optimistic locking. So
there are no approvals.
Um anyone can ship anything
but
they have to tell the organization that
they're going to do it and the
organization can veto things. And so
vetos actually kind of sounds scary and
weird but it's really empowering, right?
Right? Like if the legal team, they says
like like most of the time they say,
"Yeah, I mean this sounds totally
reasonable. I don't need to spend any
time on it." Right? But sometimes
they'll say, "Oh my god, you cannot ship
this to like children in North Korea."
Um like there there's a there's a like,
you know, sometimes that's true, right?
But uh um but if you have a process
where legal has to say yes,
uh then you have to wait for them and
like there's this round trips and
they're on vacation and like whatever,
right? It's it's it's complicated if you
say well no you can always say this is
not okay but you have to you know do you
have to now be an active actor in this
process you kind of it's both empowering
for the for those teams but also puts
the the responsibility
>> well that's interesting and so
like you guys are like ultimately you're
an infrastructure and devops corporation
how do you see the role of like reli
iability and maybe moving a little bit
slowly and and more conservatively for
the uptime of all of your customers
versus like wanting to move really
quickly in this age of agentic coding.
>> Yeah, I think the the it's it's just not
right to take those things to be in
opposition.
But like essentially everything like
everything we do in our business um and
we we have this like kind of maybe
great situation where like it's our
business to make our customers move fast
and we're taking advantage of it
ourselves, right? We're own first
customers. And so everything I do is I
think about how can I make my teams move
faster? Um how can I, you know, improve
the speed of the inner loops? How can I
improve the speed of the of the outer
loops of shipping? And so like if I uh
like that doesn't mean I never make a
trade-off, right? Like for example, we
only ship our um like serving systems
once a day, right? Um whereas we ship
our control plane every time time
someone pushes to to main. And so would
I love to be able to, you know, make a
new feature in our um consumer serving
stack on a like 15 times a day? Yes. But
you know we did make some trade-offs
there. So obviously there's you make
some decisions but it doesn't mean that
in in like that you cannot move fast and
uh you know not break things right like
there is it's possible.
>> Well you know um I did a deep dive into
Cloudflare's outage and it turns out
that it was some bad data in the control
plane twice. Um and uh the whole reason
they had the dynamic configuration was
that they could move really quickly and
make changes and customers would see
that reflected really quickly. But you
know this globalized like key value pair
store that is storing these
configurations has the potential to take
out 20% of the internet. And so do you
make a distinction between the ops and
the devops part side of the corporation
and then the the software and the
engineering and the architecture? Are
those the same thing? No, it's a really
good question. I think the like also
from my experience at Google like every
time Google goes down which you know at
at a at a large scale only happens maybe
like every five years, right? Every
single time there's it's one of two
things. It's either like a bad config
change or it is like something around
the like like secrets management service
that everything depends on, right? or
it's a config change of the secrets
management service which I think was the
last big one. Right. Right. So it's it's
always going to be that. Um and so I
mean in Verscell's architecture
we uh so we operate 20 regions 20 core
regions and so on the serving stack
again we we have deliberately decided
that we want these regions to be
autonomous and we don't have a mechanism
to change them all at once and so we uh
we thankfully cannot do these type of
confict changes that break everything at
once and so we we change them in waves
and so yeah there's another like kind of
deliberate decision to say okay we um if
I want to move fast I want to be able to
get get relatively quick feedback on my
config changes right let's say feature
flex for example and so but for that
like to get that feedback you actually
don't have to ship it globally right
it's completely sufficient to say um you
know maybe I only put it into one region
and see what happens Um and then
obviously when that region goes down we
can easily just take it out of the
rotation. And so like you can I think
every time you you do something it's
obviously important to think about like
what is the what's the risk profile and
can I find a way to make essentially
progress at the same velocity but
without taking down the risk of for
example global outages of 20% of the
internet.
>> Are you one of these shops that give
unlimited tokens to your devs?
Absolutely. We even put it into our uh
job description on
I I could not see why I could possibly
not want that. I mean, obviously people,
you know, there's always going to be
people who abuse some policy, but like I
mean, how much could it be?
>> I don't know. You're the CTO. Don't you
know about your cost?
>> No, we had a guys like basically people
like mostly it's it's bucks, right? Like
I had a engineer who was 10x the second
one was like first of all I was
impressed. Um, second of all, we found
out that his um custommade coding
harness uh had like was changing the
prefix of the prompt so that it wasn't
hitting the caching um system
>> and so which is drastically more
expensive, right? Um so obviously it
happens but yeah I think it's worth
having an eye on it but otherwise um I
think the the more the marrier.
Are your code changes uh going into
production? The CEO's code changes, are
they going into production?
>> Uh
so my CEO I think still deploys an app
to Versell every day. Um but he very
very rarely does production code
changes. And I do
I mean regular about you know maybe two
three times a week.
>> Okay.
>> Nothing nothing super big. Um, I think
it's a really common profile people in
the room will have where you say, "I do
things, but not the ones that actually
are important."
>> What do you think the future of your
tech organization is going to look like
as these agentic tools just get more and
more powerful?
I think what's already happening is that
there is like the job is just looks much
more like management than it looks like
I see work
and that I think does kind of change a
lot about the profile of the of the
people and so we what we see is that um
the the most senior IC's are in a way
the one that benefit the post because
they're they kind of already did a very
similar job, but now they have just more
minions. Um, and then and then the other
folks who benefit the most are the the
most junior engineers. Um, because they
for the same reason that they're better
at making Tik Tok videos than me, right?
Like they're growing up with that stuff.
Um, I think what what's most interesting
is kind of what happens in the in the
middle. um like where people have to
still learn to be in this in a way new
role and also
have a kind of a um you know or need to
be just willing to engage with the
technology.
>> So are you one of these companies that's
really leaning heavily into interns and
junior engineers?
Yeah, we I mean I I I'm
year over year very very impressed with
the internship program. Um and yeah, we
also have um like a pretty very very
decent cohort of junior engineers.
>> So in terms of your organization,
what does it look like in a year? What
does it look like in two years?
>> Obviously, I don't know. Um my my CEO
and I have this quasi joke that we So
right now we're like 750 people and we
just quote unquote decided that we cap
employee count at 1,024.
>> Nice round number.
>> Um
which which is notably below our hiring
plans for this year. Um so we'll we'll
see what actually happens. Um but so I I
I I could see right that there's
essentially this asmtote right where
like you know you you grow the company
but at some like the the growth kind of
even let's hopefully our growth as a as
on the revenue side kind of keeps
growing up but that maybe you you
actually don't need more people. Uh I is
it realistic?
uh like I it's like we we I mean we so
we see agentic transformation obviously
on the coding side everyone here does um
we
automated for example our uh sales leads
qualification with an agent that we also
open sourced um we automated 87% by now
of our support intake um and that you
know that's actually good example for
did we let support agent go no A I mean
first of all the company's growing fast
enough that you know that would never be
necessary and B they have a much better
job now because they only have to solve
the hard problems which I think as a
support engine you enjoy more but the um
so I think there are some factors that
kind of are you know at least reducing
growth and so I do I do think there is
going to be a transformation on that on
that line
otherwise my like the real journey that
I we're all on is that we're figuring
out how elastic the software market is,
right? because we are making it cheaper
to make software and the like what's
definitely true and I think we're very
much seeing this also in our own numbers
is that leads to more software and and
so you
like the question is like you know
obviously that's going to balance out at
some point on some equilibrium and it's
completely unclear to me right now if
that equilibrium has more software
engineers than today or fewer but it's
very possible that it's power. Um, and
it's also very possible it's fewer,
right? like but but it's I I I I I
couldn't tell how because the
like the maintenance burden that is
associated with all that free free
software is very substantial and but
also like you know as long as it gains
the productivity wins it's not worth
investing in it having people who manage
it and so forth like
>> yeah I can see how you're positioned to
support all of this new software that's
going to be created So I'm pretty
bullish on that. But yeah, I just think
the the big question about whether we're
software light or software heavy in this
new world where software is free. I
think of it sometimes like like YouTube,
right? So you know before it was very
very expensive to create a you know TV
show or a movie and now anybody can do
it. And so turns out we were actually
video light in 20 2005 or 2006 when when
YouTube came out. And I do think, you
know, nobody knows the future, but um if
we are software light, it's going to be
pretty great.
>> That's I love that analogy, right?
That's exactly my point, right? There's
going to be more software. And you know,
there's now like the number of people
that are engaged in professional video
production is drastically higher than it
was 20 years ago. Um and again like
they're they're um that doesn't mean
there's no changes, right? I think when
uh like to quote kind of Ben Thompson
who I think is making this really good
analogy that the transformation is
probably closer to the one in the 60s
when the main frames were introduced and
the buildings full of quote unquote
computers
>> um you know no longer had a job. Then it
is like the transformation of the
introduction of the internet. Um but and
so that if you look back at the
transformation in the 60s um that was
very painful for some folks, right? But
like but overall from a from a societal
perspective obviously everyone's
drastically richer now. Um so in the
long term it goes well and so I think we
you know there there's a possibility of
of a transformation that's very similar.
Last question for me. What's your
prediction about the future? That's uh
that's a hot take that you haven't
shared with anybody else yet.
>> That's difficult because I tweet
everything out immediately.
>> Oh, okay. Oh, your spiciest tweet then.
Uh
I think what I like in my in recent
world like I think like definitely um
it's
certainly the the point is that software
you know you already mentioned it's free
I mentioned it's free I think we all
realize it's free like giving getting a
free puppy right like it has to be it
has to be maintained and so I think I
mean I'm I'm very excited about the
uh the role of
agents in software maintenance and
exploring that. Um and we touched on
like how does stuff happen in
production? Uh can I can I automatically
maintain something? Um and yeah and I I
want to I mean but otherwise I'm I'm
just in the same position as everyone
like I I now get an engineer saying I
build a new file system and they
wouldn't have done that before, right?
like it would have been just too much
work or like it would have been on the
plan that took them six months. Um, but
yeah, I don't I know it's not a spicy
take, but I really I really want to
figure out like what do I do with that
file system? Like can I ship it now? Um,
or or am I now in a like or or is it
actually not real?
Ask follow-up questions or revisit key timestamps.
The video discusses the evolving landscape of coding agents and application development. It covers Vercel's internal data agent (DZero) and its public-facing product (Vercel Zero). Initially, DZero was a text-to-SQL engine that proved to be complex. Vercel then transitioned to a simpler, more declarative model based on YAML files and LLMs, which significantly improved its effectiveness. The discussion highlights the need for humility and adaptability in the rapidly changing AI field, emphasizing that current best practices can quickly become outdated. Vercel Zero, initially intended for front-end engineers, found its niche with back-end engineers and has since evolved to support full-stack app development, driven by advancements in LLM capabilities. The conversation also touches upon Vercel's operational philosophy, focusing on empowering individual engineers, optimistic locking for shipping code, and a deliberate approach to managing infrastructure to ensure reliability. The future of tech organizations is seen as increasingly management-oriented, with AI agents augmenting both senior and junior engineers. Vercel is exploring the role of agents in software maintenance and the concept of 'self-driving infrastructure,' while acknowledging the potential for increased software creation leading to new opportunities and challenges in the market.
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