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APIs · head to head

Asyncapi vs Zeplo

Asyncapi logo

Asyncapi

APIs

Specification and tools for defining asynchronous APIs

From
Free
Rated
-
Full reviewWebsite
Zeplo logo

Zeplo

APIs

Message queue as a URL prefix, adding retries and delays to any HTTP request

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; Zeplo zeplo sits directly in the execution path of your background work, so an outage at a very small vendor means your jobs do not run at all, and there is no published SLA below Enterprise.
  • They diverge on capability: Asyncapi covers API Specification, Zeplo covers URL prefix interface.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Asyncapi and Zeplo actually diverge.

Attributes where Asyncapi and Zeplo differ
AttributeAsyncapiZeplo
Pricing modelopen-sourcePer month by request count
PlatformsWeb, CLI, IDE ExtensionsWeb, Cloud
Founded2019Unknown

Identical on both: starting price (Free), 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 Asyncapi

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

Only in Zeplo

  • URL prefix interface
  • Retries with backoff
  • Delayed delivery
  • Cron scheduling
  • Concurrency limits
  • Deduplication keys
  • Request logs
  • Team workspaces

What people use each for

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

Asyncapi

  • API Developmentnot Zeplo
  • API Gatewaynot Zeplo
  • API Testingnot Zeplo
  • API Documentationnot Zeplo
  • Microservicesnot Zeplo

Zeplo

  • A Vercel or Cloudflare Workers application that needs retried background jobs without deploying a separate always-on workernot Asyncapi
  • A team that wants a webhook receiver protected by a concurrency limit so a burst does not overwhelm a downstream APInot Asyncapi
  • A small product needing cron jobs against HTTP endpoints without adding a scheduler to its infrastructurenot Asyncapi
  • A developer adding idempotent retries to an unreliable third-party API call with a one-line URL changenot 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

Zeplo

  • Zeplo sits directly in the execution path of your background work, so an outage at a very small vendor means your jobs do not run at all, and there is no published SLA below Enterprise.
  • The free Developer tier includes only 500 requests a month and one team member, so it is a demonstration allowance rather than a usable free plan for anything real.
  • Overage on the Developer tier is 20 US dollars per 100,000 requests, two hundred times the marginal rate on the Company tier, so exceeding the free allowance without upgrading is expensive.
  • Team members cost 15 US dollars each beyond the plan allowance, which is an odd charge on an infrastructure product billed by request volume.
  • Log retention is 30 days on both published tiers, so anything requiring longer audit trails on job execution has to be logged separately.

Pricing, plan by plan

Asyncapi

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

Zeplo

Free
  • DeveloperFree
    • 500 requests a month included
    • $20 per additional 100,000 requests
    • 1 team member
  • Company$39/month
    • 1,000,000 requests a month included
    • $10 per additional million requests
    • Up to 3 team members
  • Enterprise$undefined/month
    • Volume discounts
    • Custom team size
    • Support with SLA

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 Zeplo if

  • You need url prefix interface.
  • You want to start without paying.
  • You work on Web, Cloud.
  • You also want retries with backoff.
Zeplo review

Questions people ask

Is Asyncapi or Zeplo better?
Neither clearly leads. Asyncapi starts at Free and Zeplo at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Asyncapi or Zeplo?
Asyncapi starts at Free and Zeplo at Free.
Does Asyncapi or Zeplo run on more platforms?
Asyncapi runs on Web, CLI, IDE Extensions. Zeplo runs on Web, Cloud.
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 Zeplo is typically brought in for.
What can Asyncapi do that Zeplo cannot?
Asyncapi covers API Specification, Code generation, Documentation, Multiple messaging protocols. Zeplo covers URL prefix interface, Retries with backoff, Delayed delivery, Cron scheduling.

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
Zeplo: How does Zeplo work?

You prefix your endpoint URL with zeplo.to and add query parameters for retries, delay, cron or concurrency. No SDK or broker is needed.

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
Zeplo: What does it cost?

Free for 500 requests a month; 39 US dollars a month for a million requests, then 10 dollars per additional million.

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
Zeplo: Is it suitable for critical jobs?

It is a small vendor in your execution path with no published SLA below Enterprise, so weigh that against the convenience.

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
Zeplo: Does it work with serverless platforms?

Yes, that is its main use, covering Vercel, Cloudflare Workers, Netlify and similar environments that lack long-running workers.

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