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Ably vs Stainless

Ably logo

Ably

Software

Realtime data delivery platform for pub/sub messaging at scale

From
Free
Rated
-
Full reviewWebsite
Stainless logo

Stainless

Software

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

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Ably standard and Pro plans layer usage-based charges for messages, connection minutes, and data transfer on top of the base subscription, adding cost complexity.; Stainless starter and Pro plan prices are not published and require contacting the company.
  • They diverge on capability: Ably covers Pub/sub messaging, Stainless covers SDK generation.

Where they differ

Only the attributes on which Ably and Stainless actually diverge.

Attributes where Ably and Stainless differ
AttributeAblyStainless
Platformsweb, ios, android, apiweb, api

Identical on both: starting price (Free), pricing model (freemium), free tier (Yes), user rating (Not yet rated), category (Unknown).

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 Ably

  • Pub/sub messaging
  • Presence
  • Message persistence
  • Multi-protocol support
  • Encryption
  • Datadog integration

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.

Ably

  • Building realtime chat or collaborative appsnot Stainless
  • Delivering live data feeds like stock prices or sports scoresnot Stainless
  • Broadcasting notifications to many concurrent clientsnot Stainless
  • Running mission-critical realtime infrastructure with high uptime SLAsnot Stainless

Stainless

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

Where each one falls short

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

Ably

  • Standard and Pro plans layer usage-based charges for messages, connection minutes, and data transfer on top of the base subscription, adding cost complexity.
  • The jump from Standard ($29/month) to Pro ($399/month) is steep for teams needing more than 10k connections but not full Pro capacity.
  • 24/7 mission-critical support and 99.999% uptime SLAs are reserved for the custom-priced Enterprise tier.

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

Ably

Free
  • FreeFree
    • 200 concurrent connections
    • 500 messages/second
    • 6M messages/month
  • Standard$29/month
    • 10k concurrent channels
    • 10k concurrent connections
    • 2.5k messages/second
  • Pro$399/month
    • 50k concurrent channels
    • 50k concurrent connections
    • 10k messages/second

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 Ably if

  • You need pub/sub messaging.
  • You want to start without paying.
  • You work on web, ios, android, api.
  • You also want presence.
Ably review

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

Questions people ask

Is Ably or Stainless better?
Neither clearly leads. Ably starts at Free and Stainless at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Ably or Stainless?
Ably starts at Free and Stainless at Free.
Does Ably or Stainless run on more platforms?
Ably runs on web, ios, android, api. Stainless runs on web, api.
Can I use Ably for free?
Both have a free tier, so you can try either at no cost before committing.
What is Ably best used for?
Ably is most often used for building realtime chat or collaborative apps, delivering live data feeds like stock prices or sports scores, broadcasting notifications to many concurrent clients, running mission-critical realtime infrastructure with high uptime slas. Of those, building realtime chat or collaborative apps and delivering live data feeds like stock prices or sports scores are not what Stainless is typically brought in for.
What can Ably do that Stainless cannot?
Ably covers Pub/sub messaging, Presence, Message persistence, Multi-protocol support. Stainless covers SDK generation, MCP server generation, Docs site generation, Webhooks and streaming support.

Answered from the vendors’ own pages

Ably: What does Ably cost?

Ably offers a free plan with 200 concurrent connections, a Standard plan at $29/month plus usage, a Pro plan at $399/month plus usage, and custom Enterprise pricing with unlimited channels and connections.

Source
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
Ably: Is there a free plan, and what are its limits?

Yes, the free plan includes 200 concurrent connections, 500 messages per second, and 6 million messages per month with community and best-effort email support.

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
Ably: How is usage metered?

Beyond plan limits, Ably charges usage-based rates of $2.50 per million messages, $1.00 per million connection minutes, $1.00 per million channel minutes, and $0.25 per GiB of data transfer, with volume discounts available.

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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