The company and program
| Client | A Series B AI coding tool: a coding agent for the IDE and terminal, sold per seat. |
| Stage | Series B |
| Industry | AI coding tools |
| Timeline | One quarter, Q3 2026 (13 weeks): weeks 1–3 tests, weeks 4–13 scale |
| Channels | YouTube in-stream ads (creator build cut-downs and a brand demo); Reddit promoted posts |
| Team | A Kiko growth lead and a paid media buyer, plus agents for creative tagging, spend pacing and the weekly paid-seat report |
The approach
- Hypothesis: developers trust a real build in someone else's repository more than a polished brand demo, and a Reddit post that reads like release notes more than an image ad. Both should lower cost per paid seat, not only cost per sign-up.
- Comparison: on YouTube, creator build cut-downs against the brand's own terminal demo. On Reddit, text posts (a changelog, a benchmark thread) against image ads with a speed claim. Both channels against the prior quarter's Google search and LinkedIn program.
- Decision rule: each concept got 7 days or $1,000, whichever came first, judged on first accepted edit within 7 days. Kill any concept more than 30% above the best one on its channel. From week 4, budgets moved weekly toward the lowest cost per paid seat, in steps of no more than 20%.
What we changed
- Weeks 1–2: events and creators. We sent "first accepted edit" and "paid seat" server-side to YouTube and Reddit. Four developer YouTubers at 250K–600K subscribers each fixed something real in an open-source repository on camera. The base fee included 90 days of paid usage.
- Weeks 1–3: tests. We ran 11 YouTube cut-downs and 9 Reddit posts. Reddit image ads with a "10x faster" claim were killed in week 2.
- Weeks 4–13: scale. Weekly spend rose more than 40% behind the winners, with new cut-downs every two weeks. YouTube Shorts placements were excluded from week 5.
- Every week: the seat report. Paid seats by campaign, cost per seat and the share of sign-ups that made a first accepted edit went to the client's head of growth each Monday.
The results
| Metric | Before (Q2, Google search and LinkedIn) | After (Q3, YouTube and Reddit) | Change |
|---|---|---|---|
| Sign-ups | 38,000 | 161,800 | 4.3x |
| Sign-up to first accepted edit (7 days) | 31.0% | 45.0% | +14 pts |
| Paid seats | 2,054 | 8,900 | 4.3x |
| CAC per paid seat | $185.00 | $118.00 | −36% |
| CAC payback at $24 a seat a month | 7.7 months | 4.9 months | −2.8 months |
YouTube brought 5,600 seats at $112.50. Reddit brought 3,300 at $127.33, with cheaper sign-ups ($5.40 against $7.50) that converted to paid seats less often.
What didn't work
- Speed claims on Reddit. Image ads promising "10x faster" drew clicks, then hostile comment threads and almost no first edits. They were killed in week 2.
- YouTube Shorts. Shorts placements gave the cheapest views and sign-ups, but only about 1% of those sign-ups became paid seats. We excluded them from week 5.
- Creator cut-downs on Reddit. The same videos that won on YouTube cost $146.03 per seat on Reddit, 23% above the best text post. Reddit readers wanted text and numbers they could check.
What we learned
- Pay creators to fix something real in a public repository, and license the run for paid use from the start.
- Write Reddit ads as release notes, with numbers a developer can verify.
- Judge on paid seats from server-side events. Cost per sign-up pointed to the wrong channel all quarter.
Frequently asked questions
How much does it cost to buy paid seats for an AI coding tool on YouTube and Reddit?
In this quarter, $118 per paid seat: $112.50 on YouTube and $127.33 on Reddit, down from $185 on Google search and LinkedIn. At $24 a seat a month, that pays back in 4.9 months.
How fast does CAC payback improve?
Within one 13-week quarter. Weeks 1–3 were tests, weeks 4–13 scale. Payback at $24 a seat a month fell from 7.7 months to 4.9 months over the quarter.
Would this work for a seed-stage AI coding tool with a smaller budget?
The channel choice yes, the pace no. This program bought seats at a volume most seed budgets can't match, and the 20% weekly budget steps assume that scale. Reddit also needs text posts with checkable numbers, since creator videos cost $146.03 per seat there.
Related case studies and guides
Same industry, other angles:
- Creator marketing: 11,200 sign-ups in launch month, 38% from creator links
- Product growth: Free-to-paid conversion up from 3.1% to 6.8% in a 90-day sprint
- Full growth system: grew to 1,900 paying teams in 6 months