APIs · head to head
Basis Theory vs Stainless
Basis Theory
APIs
Developer tokenisation platform that holds card and sensitive data inside a PCI Level 1 environment you do not operate
- From
- $995/month
- Rated
- -
Stainless
APIs
Generates client SDKs, API docs, and MCP servers from an OpenAPI spec
- From
- Free
- Rated
- -
The short version
- Only Stainless has a free tier, so it costs nothing to try first.
- Each has a real cost: Basis Theory the Starter plan is 995 US dollars a month before any volume, which is a real floor for an early stage company and puts the product out of reach of teams tokenising a few thousand records.; Stainless starter and Pro plan prices are not published and require contacting the company.
- They diverge on capability: Basis Theory covers Tokenisation API, Stainless covers SDK generation.
- Prices and features above were last checked on 31 August 2026.
Where they differ
Only the attributes on which Basis Theory and Stainless actually diverge.
| Attribute | Basis Theory | Stainless |
|---|---|---|
| Starting price | $995/month | Free |
| Pricing model | Per month by token volume | freemium |
| Free tier | No | Yes |
| Platforms | Web, iOS, Android, Linux | web, api |
Identical on both: user rating (Not yet rated), category (APIs).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Basis Theory
- Tokenisation API
- Hosted elements
- Outbound proxy
- PCI attestation of compliance
- Processor portability
- Reactors
- Access controls and audit
- PII and PHI options
Only in Stainless
- SDK generation
- MCP server generation
- Docs site generation
- Webhooks and streaming support
- Automated unit tests
- Git integration
What people use each for
The jobs each tool is most often brought in to do.
Basis Theory
- A payments company that wants card on file without bringing its own infrastructure into PCI scope and paying for the assessment that followsnot Stainless
- A merchant locked into a processor by that processor vault that wants to hold its own tokens and route to more than one acquirernot Stainless
- A fintech collecting bank account and identity data that needs it isolated from its application database before an enterprise security reviewnot Stainless
- A team that needs to send stored card data to a third party for a one-off integration without that data traversing its own serversnot Stainless
Stainless
- Generating typed SDKs for a public APInot Basis Theory
- Producing an MCP server from an existing OpenAPI specnot Basis Theory
- Building an API documentation site alongside client librariesnot Basis Theory
- Giving open-source APIs a free SDK generation pathnot Basis Theory
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Basis Theory
- The Starter plan is 995 US dollars a month before any volume, which is a real floor for an early stage company and puts the product out of reach of teams tokenising a few thousand records.
- Starter is limited to the US region, so a company with European data residency requirements is pushed into a quoted Scale or Enterprise agreement immediately.
- Log retention on Starter is 24 hours, which is well below what most security teams expect for a system holding cardholder data and forces an upgrade for reasons unrelated to volume.
- Migrating away means moving card data out of the vault, which requires processor and assessor involvement and is slow, so the portability argument that attracts buyers cuts against them at exit.
- An attestation of compliance covers the vendor environment, not your assessment; your assessor still decides what is in scope, and buyers occasionally discover their integration pattern pulled systems back into scope anyway.
Stainless
- Starter and Pro plan prices are not published and require contacting the company.
- The free plan caps APIs at 25 endpoints, which excludes larger production APIs.
- Overage charges apply per SDK/endpoint/month once limits are exceeded, which can make costs unpredictable at scale.
Pricing, plan by plan
Basis Theory
$995/month- Starter$995/month
- 20,000 tokens included
- Production PCI Level 1 environment
- US region only
- Scale$undefined/month
- Quoted
- Higher token volumes
- Additional regions
- Enterprise$undefined/month
- Quoted
- Additional compliance options for PII and PHI
- Responses for 95 percent of PCI SAQ D
Stainless
Free- FreeFree
- Up to 5 generators (SDKs, docs, or MCP servers)
- 5 seats
- APIs with 25 or fewer endpoints
- Starter$undefined/mo
- Unlimited generators
- Expanded seats
- Private SDKs of any size
- Pro$undefined/mo
- Custom enterprise features and pricing
- Enterprise$undefined/mo
- Dedicated support
- SOC 2 compliance reports
- Purchase order/invoicing with negotiable terms
Which should you pick?
Choose Basis Theory if
- You need tokenisation api.
- You work on Web, iOS, Android, Linux.
- You also want hosted elements.
Choose Stainless if
- You need sdk generation.
- You want to start without paying.
- You work on web, api.
- You also want mcp server generation.
Questions people ask
- Is Basis Theory or Stainless better?
- Neither clearly leads. Basis Theory starts at $995/month and Stainless at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Basis Theory or Stainless?
- Stainless has a free tier; the other does not. Paid plans start at $995/month for Basis Theory and Free for Stainless.
- Does Basis Theory or Stainless run on more platforms?
- Basis Theory runs on Web, iOS, Android, Linux. Stainless runs on web, api.
- Can I use Stainless for free?
- Yes. Stainless has a free tier, so you can try it without paying. Basis Theory starts at $995/month.
- What is Basis Theory best used for?
- Basis Theory is most often used for a payments company that wants card on file without bringing its own infrastructure into pci scope and paying for the assessment that follows, a merchant locked into a processor by that processor vault that wants to hold its own tokens and route to more than one acquirer, a fintech collecting bank account and identity data that needs it isolated from its application database before an enterprise security review, a team that needs to send stored card data to a third party for a one-off integration without that data traversing its own servers. Of those, a payments company that wants card on file without bringing its own infrastructure into pci scope and paying for the assessment that follows and a merchant locked into a processor by that processor vault that wants to hold its own tokens and route to more than one acquirer are not what Stainless is typically brought in for.
- What can Basis Theory do that Stainless cannot?
- Basis Theory covers Tokenisation API, Hosted elements, Outbound proxy, PCI attestation of compliance. Stainless covers SDK generation, MCP server generation, Docs site generation, Webhooks and streaming support.
Answered from the vendors’ own pages
Basis Theory: Does this make us PCI compliant?
It removes cardholder data from your systems and gives you an AOC plus documented responses for most of a SAQ D. Your assessor still determines your scope, and a careless integration can pull systems back in.
Stainless: Is there a free plan, and what are its limits?
Yes. The Free plan supports up to 5 generators, 5 seats, APIs with 25 or fewer endpoints, and 100 preview builds per month, with email support.
SourceBasis Theory: What does it cost to start?
995 US dollars a month on Starter, including 20,000 tokens, a production PCI Level 1 environment and US hosting. Higher tiers are quoted.
Stainless: Who owns the generated SDK code?
The generated SDK code is owned by the customer and published by Stainless under the Apache 2.0 license.
SourceBasis Theory: Can we switch payment processors without re-collecting cards?
Yes, that is the main non-compliance reason to buy it. You hold the tokens and detokenise into whichever processor you route to.
Stainless: What happens if I exceed my plan's endpoint limit?
Customers exceeding their endpoint limits are billed per SDK, per endpoint, per month for the overage.
SourceBasis Theory: Is data stored outside the United States?
Not on Starter, which is US only. Other regions require a Scale or Enterprise agreement.
Related pages
More on Basis Theory
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