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APIs · head to head

Stainless vs Thunder Client

Stainless logo

Stainless

APIs

Generates client SDKs, API docs, and MCP servers from an OpenAPI spec

From
Free
Rated
-
Full reviewWebsite
Thunder Client logo

Thunder Client

APIs

Lightweight REST API client built as VSCode extension

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Stainless starter and Pro plan prices are not published and require contacting the company.; Thunder Client paid plans are billed annually only: Starter is $3 per user per month and capped at a maximum of 10 seats, Business is $7 per user per month with 500 monthly collection runs per user, and Enterprise is $16 per user per month for unlimited runs
  • They diverge on capability: Stainless covers SDK generation, Thunder Client covers REST Client.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Stainless and Thunder Client actually diverge.

Attributes where Stainless and Thunder Client differ
AttributeStainlessThunder Client
Platformsweb, apiVSCode extension, Web
FoundedUnknown2021

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), 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 Stainless

  • SDK generation
  • MCP server generation
  • Docs site generation
  • Webhooks and streaming support
  • Automated unit tests
  • Git integration

Only in Thunder Client

  • REST Client
  • Environment variables
  • Response testing
  • VSCode
  • GitHub
  • Webhook support
  • VSCode extension support
  • Web support

What people use each for

The jobs each tool is most often brought in to do.

Stainless

  • Generating typed SDKs for a public APInot Thunder Client
  • Producing an MCP server from an existing OpenAPI specnot Thunder Client
  • Building an API documentation site alongside client librariesnot Thunder Client
  • Giving open-source APIs a free SDK generation pathnot Thunder Client

Thunder Client

  • API Developmentnot Stainless
  • API Gatewaynot Stainless
  • API Testingnot Stainless
  • API Documentationnot Stainless
  • Microservicesnot Stainless

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

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.

Thunder Client

  • Paid plans are billed annually only: Starter is $3 per user per month and capped at a maximum of 10 seats, Business is $7 per user per month with 500 monthly collection runs per user, and Enterprise is $16 per user per month for unlimited runs

Pricing, plan by plan

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

Thunder Client

Free
  • FreeFree
    • REST client
    • Collection management
    • Local testing
  • Pro$8/monthly
    • Cloud sync
    • Team collaboration
    • Advanced features

Which should you pick?

Choose Stainless if

  • You need sdk generation.
  • You want to start without paying.
  • You work on web, api.
  • You also want mcp server generation.
Stainless review

Choose Thunder Client if

  • You need rest client.
  • You want to start without paying.
  • You work on VSCode extension, Web.
  • You also want environment variables.
Thunder Client review

Questions people ask

Is Stainless or Thunder Client better?
Neither clearly leads. Stainless starts at Free and Thunder Client at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Stainless or Thunder Client?
Stainless starts at Free and Thunder Client at Free.
Does Stainless or Thunder Client run on more platforms?
Stainless runs on web, api. Thunder Client runs on VSCode extension, Web.
Can I use Stainless for free?
Both have a free tier, so you can try either at no cost before committing.
What is Stainless best used for?
Stainless is most often used for generating typed sdks for a public api, producing an mcp server from an existing openapi spec, building an api documentation site alongside client libraries, giving open-source apis a free sdk generation path. Of those, generating typed sdks for a public api and producing an mcp server from an existing openapi spec are not what Thunder Client is typically brought in for.
What can Stainless do that Thunder Client cannot?
Stainless covers SDK generation, MCP server generation, Docs site generation, Webhooks and streaming support. Thunder Client covers REST Client, Environment variables, Response testing, VSCode.

Answered from the vendors’ own pages

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.

Source
Thunder Client: How much does Thunder Client cost?

Thunder Client publishes a free plan at no cost, then Starter at $3, Business at $7 and Enterprise at $16, all priced annually.

Source
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.

Source
Thunder Client: Is Thunder Client free?

Yes, there is a free plan. It is used through the Thunder Client extension for VS Code, available from the marketplace, with limits applied compared with the paid tiers.

Source
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.

Source
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