Three kinds of "free" show up when you search for a free Stainless alternative: a real unlimited free tier (Fern's docs plan, OpenAPI Generator, Kiota), a capped free tier that gates you out fast (Stainless's 25-endpoint limit, Scalar's 3-API cap), and a free trial dressed up as free (Speakeasy's 14-day business-tier trial). Sourced's free tier is unlimited SDK and docs previews plus two hosted noindex docs sites, no credit card — the only tier in the table below that pairs "unlimited" with "no card" outright, among the platforms compared here. This post lists what each actually excludes, verified against their pricing and docs pages as of September 2026.
Read the Stainless row below with one update: Stainless is no longer a live option for new evaluations. Per their announcement, Stainless is joining Anthropic and, as of that post, new signups, projects, and SDKs stopped — the free tier described here is closed to anyone who doesn't already have an account. WorkOS's coverage of the acquisition is blunt about it: the hosted SDK generator is going away. If you're comparing free tiers to start something new, treat Stainless as unavailable and look at the other nine rows; existing Stainless customers can read the migration guide for what stays portable.
The free-tier table
| Tool | Free tier | What free excludes |
|---|---|---|
| Sourced | Unlimited SDK/docs previews, 2 hosted noindex docs review sites, no credit card | Production custom domain, npm/PyPI publishing, GitHub repo sync, team seats |
| Stainless | 5 generators (SDK/docs/MCP combined), 5 seats, ≤25 endpoints, 100 preview builds/month | Docs features ("None included" on the free tier per their pricing page), higher endpoint counts, phone/priority support |
| Fern | $0/mo, "free forever" docs plan (only two public tiers: Free and Enterprise) | Everything above Free is unpriced — Enterprise is "Book a demo" only |
| Speakeasy | One SDK, up to 50 API methods, free of charge; new accounts also get a 14-day trial of the business tier | Self-serve pricing beyond that isn't public — speakeasy.com/pricing now presents an enterprise, contact-sales page |
| Scalar | Docs, landing pages, 1 SDK up to 25 endpoints, max 3 APIs, 1 editor seat, no credit card | More APIs, more endpoints per SDK, more than 1 editor seat, hosted MCP servers |
| ReadMe | Starter plan, $0/mo: custom domain, interactive reference, usage metrics, llms.txt, MCP Server | Team collaboration/multiplayer editing, private docs, Ask AI (a $150/mo add-on even on Starter) |
| GitBook | Free, $0/site/month: MCP server, GitHub/GitLab sync, LLM optimizations, 1 free user | More than 1 user ($12/mo each), custom domain, AI writing tools, unlimited AI Agent use (10 messages/week on free) |
| Bump.sh | No standalone free plan; qualifying open-source projects get free access to the Pro plan | Everyone else starts at $50/month (Basic) |
| OpenAPI Generator | Fully free and open source, no tiers, no caps | Hosting, publishing, compatibility diffing, support — you run and maintain it |
| Kiota | Fully free and open source, no tiers, no caps | Docs hosting, publishing automation — it's a client generator, not a platform |
Reading the caps correctly
A cap that matters on day one is different from one that matters at scale. Stainless's free tier caps at 25 endpoints and ships no docs features at all on that tier, per their own pricing page — if your API is small and you only need an SDK, that's workable; if you need docs too, it isn't, on free (moot for new users regardless, since Stainless closed new signups as of September 2026 — see above). Scalar's free tier caps APIs at three and SDKs at one language per API, which is fine for evaluating the product but not for running a real multi-service docs site. GitBook and ReadMe both put meaningful AI features behind paid add-ons even on their free tiers.
Fern is the outlier: its public pricing page, fetched directly in September 2026, shows only two tiers — Free (explicitly "free forever") and Enterprise (custom, contact sales). There's no public mid-tier price to compare against, which makes Fern either the best free option or an opaque one, depending on whether your team ever needs to grow past it.
Speakeasy's free tier is real but narrow — one SDK, 50 methods — and its pricing page has moved away from publishing self-serve numbers entirely, leading instead with enterprise AI-governance positioning. If you're comparing "free forever" options, Speakeasy's docs-stated free allowance is the number to use, not the pricing page.
Where open source actually wins on "free"
OpenAPI Generator and Kiota don't have tiers because there's no vendor metering anything. OpenAPI Generator is community-maintained, covers 50+ generators across 40+ languages, and runs from npm, Homebrew, or Docker with a single openapi-generator-cli generate command. Kiota, maintained by Microsoft, generates clients in nine languages (CSharp, Go, Java, PHP, Python, Ruby, Shell, Swift, TypeScript — maturity varies by language, from Stable to Experimental, per their docs) with a kiota generate command once installed.
Neither charges for scale, seats, endpoints, or API count, because neither hosts anything for you. That's the honest tradeoff: OSS is free of dollar limits, not free of engineering time. You still own the CI pipeline, the release process, the docs site (there isn't one), and any compatibility checking between versions. See the open-source alternative deep dive for when that tradeoff is worth it.
What "free" gets you toward hosted docs specifically
If the reason you're evaluating alternatives is hosted docs rather than just SDK generation, narrow the free-tier comparison to that:
- Sourced: up to 2 hosted noindex docs review sites and one hosted MCP server, free, alongside unlimited SDK previews.
- Fern: docs are part of the same $0/mo Free plan, unlimited in the sense that there's no published cap on the free tier itself.
- Scalar: docs and landing pages included free, capped at 3 APIs.
- ReadMe: docs included on Starter, but collaboration and most AI features are paid.
- GitBook: docs included free, capped at 1 user.
- Stainless: no docs features on the free tier at all.
Honest scope
If your team is comfortable owning a CI pipeline and template maintenance forever, OpenAPI Generator or Kiota is the actually-free path — no account, no vendor, no future price change to track. If you want hosted docs and an SDK preview without standing up that infrastructure, Sourced's free tier gets you both from one OpenAPI upload, with the tradeoff being production publishing (custom domain, npm/PyPI, team seats) sitting behind a paid plan once you're ready to ship.
FAQ
Which free tier lasts the longest without hitting a wall?
For evaluation purposes, OpenAPI Generator and Kiota have no wall — they're open source with no usage caps. Among hosted options, Fern's $0/mo Free plan has no published endpoint or API cap as of September 2026.
Does Stainless's free tier include docs?
No. Stainless's own pricing page lists "None included" for docs features on the Free plan.
Is Speakeasy's free SDK generation still available?
Yes — one SDK up to 50 API methods, per their docs, even though the pricing page itself now emphasizes enterprise AI-governance plans over self-serve SDK pricing.
Do I need a credit card for Sourced's free tier?
No. Unlimited previews and up to two hosted noindex docs sites and one hosted MCP server require no credit card.
Is open source really free, or just free of licensing cost?
Free of licensing and usage cost, not free of labor. You maintain the generator config, the CI job that runs it, and any docs site separately — see the OSS alternative post for the full tradeoff.
What happens when I outgrow the free tier on Sourced?
Publishing to npm, PyPI, or a custom domain, plus GitHub repo sync and team seats, moves to a paid plan. See Sourced vs Stainless pricing for the numbers.
Try the free tier
Create hosted docs from your repo or start free with a direct spec upload — no credit card either way. Validate your spec first with the OpenAPI validator, or generate an llms.txt file with the llms.txt generator while you're evaluating.