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Asyncapi vs PubNub

Asyncapi logo

Asyncapi

Software

Specification and tools for defining asynchronous APIs

From
Free
Rated
-
Full reviewWebsite
PubNub logo

PubNub

Software

Realtime communication platform for chat, IoT, and live data apps

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Asyncapi complex to implement and debug asynchronous operations due to their non-linear and concurrent nature; PubNub free plan storage history is limited to 7 days, which is short for apps needing longer message retention.
  • They diverge on capability: Asyncapi covers API Specification, PubNub covers Pub/sub messaging.

Where they differ

Only the attributes on which Asyncapi and PubNub actually diverge.

Attributes where Asyncapi and PubNub differ
AttributeAsyncapiPubNub
Pricing modelopen-sourcefreemium
PlatformsWeb, CLI, IDE Extensionsweb, ios, android, api
Founded2019Unknown

Identical on both: starting price (Free), 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 Asyncapi

  • API Specification
  • Code generation
  • Documentation
  • Multiple messaging protocols
  • Code generators
  • Specification support
  • Tools support
  • CLI support

Only in PubNub

  • Pub/sub messaging
  • Presence tracking
  • Message persistence
  • Serverless Functions
  • File sharing
  • Encryption and access controls

What people use each for

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

Asyncapi

  • API Developmentnot PubNub
  • API Gatewaynot PubNub
  • API Testingnot PubNub
  • API Documentationnot PubNub
  • Microservicesnot PubNub

PubNub

  • Building realtime chat applicationsnot Asyncapi
  • Streaming live IoT sensor datanot Asyncapi
  • Adding presence indicators to collaborative appsnot Asyncapi
  • Running edge logic with serverless Functions on realtime eventsnot Asyncapi

Where each one falls short

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

Asyncapi

  • Complex to implement and debug asynchronous operations due to their non-linear and concurrent nature
  • Keeping AsyncAPI documents up to date is challenging as systems evolve
  • Tracing and debugging asynchronous operations is more difficult than synchronous request-response patterns

PubNub

  • Free plan storage history is limited to 7 days, which is short for apps needing longer message retention.
  • MAU-based pricing means costs scale directly with user growth, which can be less predictable than flat message-based pricing.
  • Pro-tier custom pricing above 50,000 MAU requires contacting sales rather than self-serve checkout.

Pricing, plan by plan

Asyncapi

Free
  • Open SourceFree
    • AsyncAPI specification
    • Tools
    • Community support

PubNub

Free
  • FreeFree
    • Up to 200 MAU or 1M transactions
    • 1GB data storage (7 days)
    • 5 test Serverless Functions
  • Starter$98/month
    • 1,000 MAU included
    • User management
    • Insights
  • Pro$undefined/month
    • Custom MAU packages
    • Volume discounts
    • Enterprise-scale configurations

Which should you pick?

Choose Asyncapi if

  • You need api specification.
  • You want to start without paying.
  • You work on Web, CLI, IDE Extensions.
  • You also want code generation.
Asyncapi review

Choose PubNub if

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

Questions people ask

Is Asyncapi or PubNub better?
Neither clearly leads. Asyncapi starts at Free and PubNub at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Asyncapi or PubNub?
Asyncapi starts at Free and PubNub at Free.
Does Asyncapi or PubNub run on more platforms?
Asyncapi runs on Web, CLI, IDE Extensions. PubNub runs on web, ios, android, api.
Can I use Asyncapi for free?
Both have a free tier, so you can try either at no cost before committing.
What is Asyncapi best used for?
Asyncapi is most often used for api development, api gateway, api testing, api documentation. Of those, api development and api gateway are not what PubNub is typically brought in for.
What can Asyncapi do that PubNub cannot?
Asyncapi covers API Specification, Code generation, Documentation, Multiple messaging protocols. PubNub covers Pub/sub messaging, Presence tracking, Message persistence, Serverless Functions.

Answered from the vendors’ own pages

Asyncapi: What is AsyncAPI used for?

AsyncAPI is an open-source specification for defining and documenting asynchronous APIs, message-driven systems, and event-driven architectures. It serves the same purpose for async APIs as OpenAPI does for REST APIs, providing standardized documentation, code generation, and tooling.

Source
PubNub: What does PubNub cost?

PubNub offers a free plan for up to 200 MAU or 1 million transactions, a Starter plan at $98/month for 1,000 MAU, and custom Pro pricing for larger volumes, e.g. around $550/month for 10,000 MAU.

Source
Asyncapi: Is AsyncAPI free to use?

Yes, AsyncAPI is completely free and open-source. It is hosted by the Linux Foundation and supported by community contributions and sponsorships from companies like Postman, IBM, IQVIA Technology, and Solace.

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

Yes, the free plan supports up to 200 monthly active users or 1 million transactions, includes 1GB of data storage retained for 7 days, and requires no credit card.

Source
Asyncapi: What protocols and technologies does AsyncAPI support?

AsyncAPI supports multiple protocols and technologies including Kafka, RabbitMQ, MQTT, Socket.IO, AWS EventBridge, and others. It provides language support for JavaScript/TypeScript, Python, Java, Go, C#/.NET, Kotlin, and PHP.

Source
PubNub: How is usage metered?

PubNub bills primarily by Monthly Active Users, defined as a unique user who connects at least once in a billing cycle; messages are bundled into MAU pricing with no separate per-message fees, and overage is billed proportionally.

Source
Asyncapi: Does AsyncAPI have IDE support?

Yes, AsyncAPI has IDE extensions available for VSCode and IntelliJ, along with CLI utilities and GitHub Actions integration for developers.

Source
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