How Papermark Reached $3M ARR as a Bootstrapped, Profitable Open Source DocSend Alternative (Interview with Co-Founder Marc Seitz)

Introduction and Marc Seitz's Background

Marc Seitz

00:00You know, I wanted to build something in the open source space. My wife told me, like, you know, don't just build something. No one's gonna use it. Test it on Twitter first. If it was... Like, people like it, if they share it, comment, etcetera, then you can build it over the weekend.

Nathan Latka

00:14How many new paid customers did you add last month?

Marc Seitz

00:17We have about a 100 sign ups per day.

Nathan Latka

00:19With your current revenue growth rate, where do you think you'll finish in 2026?

Marc Seitz

00:25Probably around four, four and a half.

Nathan Latka

00:29Germans are so conservative. Come on. You're growing like crazy. You could beat five, six million. Right?

00:37Hey, folks. My guest today is Marc Seitz. He's a physicist by training and a self taught software engineer who was CTO at AlphaQ Venture Capital, cofounded Hacker Bar and helped launch Intel Ignite in Europe before starting Papermark in 2023 out of Munich. He built the first version in a single weekend after a tweet testing demand for an open source DocSend alternative. He pulled in 450 likes, more than 95,000 views, and now he runs the company with

01:01his wife and cofounder, which is awesome. Marc, you ready to take us to the top?

Marc Seitz

01:05Yeah. Absolutely. It's good.

Nathan Latka

01:07There's this old joke right now of, you know, someone launches on Twitter and says, I built the open source DocuSign and then DocuSign stock tanks like 10%. I mean, that sort of what happened here? Tell us what happened.

Tweet First, Build Second: Version One in a Weekend

Marc Seitz

01:17You know, I wanted to build something in the open source space. I really loved open source. I knew there was nobody kind of building something that would resemble like a DocSend or data room space. So what I did is, you know, my wife told me like, you know, don't just build something, no one's going to use it. But, you know, test it on Twitter first. Just write a tweet. People like it, if they share it, comment,

01:46etc, then you can build it over the weekend. We sent out that tweet, instantly got like a bunch of traction. And then I built it over the weekend, shipped it. It went, viral again. So I just kept plugging along weekends and nights. And, you know, then the first customers started saying, Hey, can we pay you money? And that eventually then turned into the business, what Papermark is today.

Nathan Latka

02:12This is such a smart go to market strategy for engineers, right? Then you measure success by, like, GitHub stars and things like that, right?

Why DocSend Was the Right Target

Marc Seitz

02:18I think open source, especially around that time, '23 maybe, you know, was already the tail end. It was really before AI got really good. So, a lot of people looked to open source, to either collaborate, contribute, but there was a whole wave of these commercial open source projects going on where you had Calendly, you had an open source alternative. And other products that were considered legacy or a bit older already, out there and just people were

02:47craving for something fresh and alternative. And so, we, I feel like we hit the momentum, like right on the nail because everyone knew DocSend and everyone didn't like it. They got acquired by Dropbox, during, you know, the COVID bubble and then, kind of stopped kind of iterating on the product.

Nathan Latka

03:04So guys, here it is. Alright. The question is when you come across a GitHub project that's open source with 8,900 stars and 60 contributors, what is that worth in terms of ARR revenue? Well, the answer is 3,000,000 of ARR. So tell us what happened. Walk us through the stages here. So you work on this on a weekend, you launch it. How did you get your first a thousand stars, Marc?

Open Source Community and GitHub Stars

Marc Seitz

03:26So we were part of this, like, open source community and I feel like that was vital in the beginning because we had each other's backs. Being open source, it's, you know, it's even better to build in public because everything is transparent down to the line of code that you're writing. So there's nothing to hide behind, so there's nothing to be ashamed of if it's not fully ready or not. And then we shared obviously our wins, our

03:47losses pretty much every month. People like following a journey and seeing like where the story ends up. Then it goes to 3,000,000. Nobody had thought at the time, but, you know, probably the first a thousand likes or so were gathered, like, were probably within the first couple of months, like one or two months or so, just off of the, you know, viral X posts. For me personally, it was like, once I hit like a thousand stars,

04:15I was kind of like validated, I was happy. I didn't need to go to 10,000 stars or more.

Nathan Latka

04:20What was the name? You said you were part of an open source community early on. What's the name of that community?

Marc Seitz

04:26I don't think we have an actual name. I mean, a lot of people that are in open source are somehow like part German. So,

04:34we kind of found each other through kind of our shared history, and then the open source or commercial open source space was pretty small.

Nathan Latka

04:43When a post goes viral like this on LinkedIn, right, do you get a bunch more revenue from this or no? It's sort of vanity.

LinkedIn Virality and Audience Building

Marc Seitz

04:50LinkedIn is very hard to track, so it's not a direct, conversion channel. Nonetheless, it does help because we do have, you know, a lot of our customers. Last time I was checked, it was like 250,000 views or so on that particular post.

Nathan Latka

05:05Would... Were you already famous before you posted?

Marc Seitz

05:09No. So, I mean, I had probably, like, crossed that, like, 1,000, follower threshold, but it took me a really long time to get, past, I think, the five k mark. None of our customers today are on Twitter itself. Most of them are on LinkedIn, so our strategy has shifted a little bit to LinkedIn.

Nathan Latka

05:27You guys are a smaller team. You have the benefit though of contributors contributing to the code base. One of the very interesting balances here, I mean, we all know about the WP Engine and Automattic sort of lawsuits going on. You know, basically, Mullenweg is upset at a high level. Mullenweg is upset that WP Engine is making so much money, and he feels like they're not contributing enough code back to the open source model. So the open

05:48source community is getting pissed. You know, as you grow in scale, how do you make sure that your open source community that's contributing to your code base doesn't feel like you're just milking money from it?

Marc Seitz

05:57Open source contributions, they also decline over time, unfortunately. That's just the nature of an open source project because in the beginning you have very little code, there's very little complexity in the project. It's very easy to contribute something new and add value. Over time, unless you stick around the project and you contribute regularly and you keep up to date, it becomes really hard to know what's going on because the code base might have drifted already in

06:26a completely different direction. So, as you can see here, you know, it's definitely a lot of the code on me. And then you've got like Cursor and CodeRabbit kind of like sneaking in there as well. So you kind of already see where that whole contribution graph is going, in the age of AI. And, unfortunately that's just the nature of it. AI can crunch a lot more, information than an individual person can understand complex relationships in a

06:54very big code base as we are already. And, that's just to the detriment of, individual contributors, unfortunately. So we do have, you know, there's opportunities for, you know, translations where you don't need so much insight into what each feature does or how they actually add value. There's obviously bug fixing, security reports, etcetera. Where I think open source is still extremely valuable is kind of that auditability, right? Like third parties can like go in, see the code

07:25base, see the code, run it through their own pen test or test suites, and then report back to us, which no proprietary software has, right? That's a huge upside for every of our customer and anyone that wants to get started in open source.

Nathan Latka

07:41How many customers are paying you today?

Marc Seitz

07:43So, we have, about, 3,000 customers, paying customers.

Nathan Latka

07:49That's incredible.

Marc Seitz

07:51Yeah.

Nathan Latka

07:52So where are you, you know, you could build anything, right? You specifically list PandaDoc alternative, DocSend alternative. Do you just go to their support forums, see what people are complaining about and then build like a free version of that? Or how do you put a product roadmap together?

Marc Seitz

08:05A lot of that initially is on instinct, right? I've been around long enough that I've used all of these tools. I had my own fair share of problems and I knew what the base case is, like what's the bare minimum that you need to get started, and where are the top players? And then, wherever you can take your own spin on things, without changing the behavior of the user too much, I feel like that's what you

08:31should do. So, we focus a lot on personalization or professionalization. We give users a custom domain out of the box. We give, users the ability to fully brand the look and feel of their data rooms and the documents that they're sharing. Whereas the incumbents, they put their own brand front and center. And that of course, you know, becomes then a differentiator down the road.

08:57But it doesn't matter until you feature complete because no one wants a half baked product to use. They need at least the same features.

Free Plan, Daily Signups and New Paying Customers

Nathan Latka

09:05How many new free trials and how many new paid customers did you add last month?

Marc Seitz

09:09We have about a 100 signups per day. So we do have a free version and, you know, a portion of those go into free trials. Others, they just stay on a free version forever and that's totally fine. We want to make it as easy as possible. DocSend eventually killed their free version. That's an opening for us, right? Nobody has a free version other than us in that market from the, you know, top players.

Nathan Latka

09:34How many total new customers last month, if you had to guess? Are we talking like a 100 or 500?

Marc Seitz

09:39About a 100 paying new customers.

Nathan Latka

09:41Okay. Interesting. And so go... Going forward, what's the growth strategy? I mean, you're you're crushing it in terms of your domain rating on SEO, you're a 73, but this is actually surprising to me. You're only getting 5,200 organic clicks according to Ahrefs. Most companies I see at a 73 DR, I mean, they're getting tens of thousands of organic inbound. So how are you signing up new trials and customers?

The Viral Loop Inside 60,000 Teams

Marc Seitz

10:01Surprisingly a lot is still organic. I mean, by now it might be word-of-mouth. We have, you know, over 60,000 teams, you know, both on the free and, kind of like the platform in total. A lot of them sharing links, that are papermark.com links, right? If they don't add a custom domain, it defaults to papermark.com. So that's, inherent viral loop for us. People that have, you know, never heard of us, they'll get a link, you know, data

10:33room document forwarded to them and then see our website. They check out, like, what is Papermark, does it fit for them? Most of the time our customers use already a comparable tool if they're in that market, So, they don't need any education. If they have a good experience as a visitor to a document or a data room, they'll most likely will have a great experience on, as an admin.

Nathan Latka

10:57Your website is really well done. You look like you're doing much more revenue than you're doing, so that's a compliment. Where did the design gene come from?

Marc Seitz

11:06That's all my wife. Yeah.

11:09There...

Nathan Latka

11:10And that's why you're gonna be married for a long time. Right? The compliments go back and forth. So do you guys just...

11:13You just split

11:14the company fifty-fifty or what?

Marc Seitz

11:15Yeah.

Nathan Latka

11:15Just on

11:16the There you go.

11:17There wasn't like... I mean, if you ever disagree, God forbid, who wins?

Marc Seitz

11:24I mean, obviously the wife. No, no, just jokes aside. I think with, two co-founders is perfect. Having been through the other combinations and solo is just, you know, it's too much burden on one person. So I like two co-founders and then doing it with your partner is especially, you know, special because, you know, already, you know, as a founder, you're fully consumed by the business or the product that you're working on and getting to

11:55share that with someone who's going through the same exact thing is amazing. For us, it was never a question whether we would, you know, do an uneven split, because that just introduces other friction.

Revenue Milestones: $1M and $2M ARR

Nathan Latka

12:07You launched the business, it looks like in 2023. When did you break 1,000,000 of revenue?

Marc Seitz

12:11September 2025.

Nathan Latka

12:14Oh, wow. Okay. So it took you a while. You were under 1,000,000 for a while. Then when did you break 2,000,000?

Marc Seitz

12:20January 2026.

Nathan Latka

12:22Wow. So most of your growth has come over the past nine months?

Marc Seitz

12:25Yeah.

Nathan Latka

12:25Intro... Okay.

The September 2025 Inflection and the 2026 Forecast

Nathan Latka

12:26Wait. I have to ask about that. What was the inflection point around September 2025 where you said, okay. We've been slaving away for two years now, revenue growth is kicking in.

Marc Seitz

12:36I think it was just, you know, good things take time and, especially in a market like ours, you have, again, feature parity to existing tooling incumbents. You need to match that and that just takes a little bit time to get there. And, yeah, once we were able to provide a complete product, people saw value instantly because, again, they knew what they wanted, and, up to that point we were missing maybe one or two features that they

13:04were really hoping for, So they still had to go to, you know, a competitor. But, you know, the moment we were able to offer that at, you know, the same price point that we can offer it, it became a no brainer.

Nathan Latka

13:17With your current revenue growth rate, where do you think you'll finish in 2026?

Marc Seitz

13:21The goal initially was, 3,500,000 ARR. So we hit three. Probably we'll get to

13:31probably around four, four and a half.

Nathan Latka

13:35The Germans are so conservative. Come on. You're growing like crazy. You could beat five, 6,000,000. Right?

Marc Seitz

13:41Alright. Alright. Yeah. Five would be probably the the best case or the the, you know, wishful case. Let's call it like that.

Failures Before Papermark and Lessons for Builders

Nathan Latka

13:48How many failures did you have before Papermark started working?

Marc Seitz

13:52Like five, six failures. I mean, you know, over a period of time, of course, Papermark was definitely kind of like a lucky break. Everything just came together. I don't know if you could replicate this in a lab or anything like that. It just felt like it was perfect timing. Building something that is inherently, you know, not AI first is, probably unthinkable today, but I'd urge anyone listening to look for these markets that are saturated. Our intention

14:26as humans, or as builders, are always to look for the next shiny thing, and AI is the shiny thing right now, so you do want to build something there. But it still requires a lot of behavioral change in your customer and your users, where, you know, there might be other markets, that are much more ripe for disruption.

Bootstrapped, Profitable and Reinvesting

Nathan Latka

14:45Are you guys bootstrapped today?

Marc Seitz

14:48Yes.

Nathan Latka

14:49Let's go. Are you profitable?

Marc Seitz

14:52Yes.

Nathan Latka

14:53Let's go. Double win. Okay. You're an ex ETF guy. What do you do at State Street? Very good firm. What do you do with the profits? You you you guys pay yourself out as dividends and reinvest elsewhere? You keep them in the company? What do you do?

Marc Seitz

15:05Yeah. So we... Up to this point, we do reinvest, quite a bit in the in the product, in the company itself, to build out, you know, distribution channels, etcetera. But obviously we, now we can afford a proper salary, that we couldn't before.

Would They Sell for $30M from Dropbox?

Nathan Latka

15:20If Dropbox sneaks into your DMs and offers you $30,000,000 all cash today, do you and your wife sell?

Marc Seitz

15:30It's a discussion we'll have.

15:34Dropbox bought DocSend for 140,000,000, so we'll probably not sell yet.

Nathan Latka

15:40What was the multiple though, the revenue multiple on that, do you know?

Marc Seitz

15:43It was, at the point it was 10. It was quite high. So they did 15,000,000 in ARR at the time. I feel like there's still a lot of market share for us to to grab. So, yeah, the opportunity is still big.

Nathan Latka

15:55You and your wife were all in on this. I mean, it's a lot of risk in terms of just managing your family, your personal expenses. Did the bank ever get so low you considered quitting?

Marc Seitz

16:05No, we did build up a pretty big buffer beforehand. Not intentional. It would just happen to be that we were in good jobs before, and we're able to save a little bit to kind of like weather the first year, on Papermark. And then we had, you know, by now we have a pretty good product feeling for the market and everything. Like I said, Papermark just kind of took off. It was just this perfect timing.

Nathan Latka

16:31Marc, we're all rooting for you, man. If people want to follow your story online, where's the best place to connect with you?

Marc Seitz

16:37LinkedIn and Twitter. So X is still where I'm probably most active and, you know, my DMs are open. I'll, you know, happily share whatever I can share in terms of advice or or feedback. I feel like that's super important. Love to give back.

Nathan Latka

16:53Marc, appreciate you taking us to the top, man.

Marc Seitz

16:56Thanks, Nathan. I loved it.

Nathan Latka

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