Product-Market Fit as Segment Territory
Treat PMF not as a binary but as territory won segment by segment, and double down hard on whatever segment is pulling.
- Difficulty
- Moderate
- Time to result
- ~months to results
- Steps
- 4
- Confidence
- 90%
In B2B, product-market fit isn't a single on/off moment; it's a map of the market where you hold strong fit in some segments and none in others. The move is to ask 'do we have fit in this specific segment and how strong,' capture that segment fully before expanding, and when one customer type pulls, focus on getting more of exactly that type rather than chasing everyone.
Origin
Karri Saarinen's view of Linear's PMF journey, reinforced by advice from Zoom founder Eric Yuan about winning one customer type (universities) at a time.
Core principles
- 01In B2B, fit varies by customer size, domain, and category, so PMF is a spectrum, not a binary
- 02You can have strong fit in early-stage startups while honestly having none in Fortune 500 accounts
- 03When a category is working, doubling down on it beats trying to serve everyone at once
- 04Look for pull, follow it, and capture that territory before expanding to a new area
How to run it
- 1
Ask fit per segment, not overall
Reframe the question from 'do we have PMF' to 'do we have fit in this specific segment, and how strong is it.'
Pro tip Being honest that you don't yet serve a large segment ('it's not really great for you right now') keeps focus and trust intact.
- 2
Pick one segment and become its default
Concentrate the first years on winning one segment completely; Linear aimed to be the default tool startups pick.
Pro tip Set the goal as 'be the default for this segment,' a concrete capture target rather than vague growth.
Watch out Don't try to address the whole market in the first months; a narrow win is more valuable than broad mediocrity.
- 3
Follow the pull and double down
When a specific customer type starts adopting you strongly (crypto companies, then AI companies), focus on getting more of exactly that type.
Pro tip Notice emergent clusters and ask what you could do differently to win more of that cluster.
- 4
Expand only once a segment is captured
After you've handled a category as much as you want, move deliberately to the next segment (e.g. from startups to hundreds/thousands-person companies).
Pro tip Treat expansion as acquiring new territory on the map, not abandoning the segment you already hold.
Watch out Expanding before you've captured your current segment spreads you thin and weakens the fit you had.
In the wild
Zoom founder Eric Yuan told Karri that in Zoom's early days one customer type (like universities) worked really well, so they focused on getting more universities rather than trying to get everyone.
→ Concentrating on a proven customer type compounded fit before expanding.
Linear spent its first two years getting strong fit in early-stage startups to become their default tool, then spent the following years working on fit for hundreds-to-thousands-person companies.
→ Won the startup segment as default, then deliberately expanded upmarket.
Common mistakes
Treating PMF as a single binary moment
Waiting to 'feel PMF' as one event misses that B2B fit exists per segment; you can be winning one category and absent in another simultaneously.
Chasing the whole market at once
Trying to serve every customer size and domain early spreads effort thin and prevents fully capturing the segment that's actually pulling.
Is it for you?
Best for
B2B/SaaS founders trying to gauge and grow product-market fit across varied customer sizes and domains
Not ideal for
Viral consumer apps where PMF really does read closer to a single take-off signal
From the transcript
“do we have the do we have the fit in this specific segments and like how strong that fit is”
“the default tool that the startups pick and I think we were able to accomplish that but we just purely focused on that segment”
“if you're doing really well in some category just like kind of double down on that”
“when they were like building Zoom early days they would get this one type of customer like I don't know maybe it's like a university”
“essentially look for poll and just follow that and pay attention to that”
From the episode
Inside Linear: Building with taste, craft, and focus
Karri Saarinen (co-founder, designer, CEO)