Slashbin vs mockbin
First, which mockbin? If you're searching for mockbin because something you had working stopped working, this is probably why: the original mockbin.org — the Mashape-then-Kong service — is gone. The hostname doesn't resolve at all as of 2026-07-30, so requests to it fail before they reach a server. Its code lives on as Kong/insomnia-mockbin (opens in a new tab), the backend behind Insomnia's API mocking, but that repository is source-visible under an enterprise licence rather than open source, and there is no hosted mockbin.org to point at any more.
The live tool people mean when they say "mockbin" today is mockbin.io (opens in a new tab), by Zuplo — a free, no-signup rebuild written explicitly because the original went away. Their README says it plainly: "At Zuplo we were big fans of mockbin.org and used it for testing APIs and doing demos. Unfortunately, it was shut down." It's MIT-licensed and self-hostable.
Slashbin isn't a drop-in replacement for either of them, and it shouldn't be. mockbin gives you a throwaway URL that captures a request so you can look at it, and mocks an API response so you can develop against it. Slashbin is the piece you keep after that: a gateway that transforms, validates, and delivers those webhooks to real destinations, with retries and replay when something breaks. If all you need is to see one request right now, mockbin.io is faster than us and always will be.
What mockbin is better at
- Zero signup, zero configuration, zero cost. Open mockbin.io, create a bin, get a URL, paste it into a vendor's dashboard. No account, no card, no project setup. Slashbin requires an account and a card for its 14-day trial — for a ten-second question, that's the wrong trade.
- Mocking an API, not just capturing one. You can specify the status code, headers, and JSON body a bin returns, or upload an OpenAPI 3.1 document and get mocks generated from its schemas and examples. Slashbin has no mocking feature at all — it receives real vendor traffic, it doesn't pretend to be a vendor.
- Free and open source, and you can run it yourself.
zuplo/mockbin(opens in a new tab) is MIT-licensed: a Next.js frontend plus an API that persists to S3-compatible storage, deployable on your own infrastructure. Slashbin has no open-source component and no self-hosted option. - Nothing to lose. A bin is disposable by design. There's no configuration to migrate, no schema to maintain, and nothing to turn off when you're finished.
What Slashbin is better at
- Being the permanent piece. A bin is a scratchpad — on mockbin.io the bin IDs live in your browser's local storage, so the list is gone the moment you switch machines or clear it. Slashbin is infrastructure your production pipeline depends on tomorrow, not a URL you throw away this afternoon.
- Transform and validate against one schema. Every inbound event is reshaped and checked against a Golden Model you define. Downstream code reads one canonical shape no matter which vendor sent it, and when a vendor renames a field, validation fails loudly at the boundary instead of quietly corrupting what's downstream.
- Deliver to real destinations with per-destination isolation. One inbound event fans out to every consumer that needs it, and a destination that starts failing is circuit-broken on its own without back-pressuring the others. See Fan-out.
- Retries you didn't have to write. Backoff, per-destination circuit breaking, and a dead-letter queue that holds the full payload until you fix the cause.
- Replay from stored history. The original payload is kept byte-for-byte. When you fix a transform, Replay re-runs stored events through the current pipeline — you don't ask the vendor to re-send.
- Auditable delivery log per attempt. For every attempt to every destination: response code, body, timing, retry count. That's the evidence that answers "did this event actually land?" three weeks later.
The short version: mockbin is where you look at a request once. Slashbin is where a request lives on its way to production destinations.
When to use which
- Is this vendor even sending anything, and what does it look like? → mockbin.io. Faster than signing up for anything, ours included.
- I need an endpoint that returns a specific response so I can build against it. → mockbin.io. That's mocking, and Slashbin doesn't do it.
- My mockbin.org URL stopped working and I need it back. → mockbin.io is the like-for-like replacement, and it's free. Come to Slashbin when the integration graduates from "does this work" to "this must keep working."
- I want to run the bin on my own infrastructure. →
zuplo/mockbin, MIT. We have no self-hosted option. - A production pipeline I rely on tomorrow. → Slashbin. Retries, replay, transform, fan-out, and a delivery log survive incidents; a disposable bin doesn't.
- Every vendor sends a different shape and my downstream code is full of adapter glue. → Slashbin. One Golden Model, validated at ingest, is the whole point.
- I need to prove what happened three weeks ago. → Slashbin. Stored payload, stored transform result, stored delivery attempts.
Plenty of engineers use both, and the sequence is usually the same one: a bin during vendor onboarding, a gateway once the integration is real.
Feature comparison
Verified on 2026-07-30 against mockbin.io (opens in a new tab) and the zuplo/mockbin (opens in a new tab) repository (MIT, last pushed 2026-06-09), plus Kong/insomnia-mockbin (opens in a new tab) for the original project's status. mockbin.org did not resolve in DNS on that date. Slashbin rows verified against the live product and pricing page the same day.
| Capability | mockbin (mockbin.io) | Slashbin |
|---|---|---|
| Instant capture URL, no signup | Yes | No — account required |
| Price | Free | Lite $10/mo (5,000 webhooks) |
| Open source and self-hostable | Yes — MIT (zuplo/mockbin) | Not offered today |
| Mock an API response, or a whole OpenAPI document | Yes — OpenAPI 3.1 | Not the product model |
| Where your list of endpoints lives | Browser local storage only | Your account, in the Console |
| Published retention window for captured requests | Not published | 7-day replay window on Lite, 30-day on Pro |
| Transform and validate against a canonical schema | Not the product model | Yes — Golden Model |
| Deliver one event to N destinations with per-destination filters | Not the product model | Yes — Fan-out |
| Retries with backoff and a dead-letter queue | Not the product model | Yes |
| Replay a stored raw payload through the current pipeline | Not the product model | Yes — Replay |
| Per-attempt delivery log (response code, body, timing) | Not the product model | Yes |
"Not the product model" means the tool isn't trying to do that job. mockbin is a capture-and-mock surface; it is not a delivery gateway, and it doesn't claim to be. That's a different shape of product, not a defect — and in the other direction, Slashbin genuinely can't mock an API for you.
Related reading
- All comparisons — every tool Slashbin is compared against, with a one-line note on who each page is for.
- Slashbin vs webhook.site — the same boundary against the inspection tool that's still actively developed. If you're choosing a bin today rather than replacing one that disappeared, start there.
- Webhook ETL — the category Slashbin fits in, and why point-to-point handlers stop scaling.
- Webhook Debugging — the four places a webhook dies, and what evidence tells them apart.
- Replay — re-drive a stored event through the current transform + delivery pipeline.
- Debug Stripe Webhooks — worked example of the four-stage debug walk against Stripe.