JSON Placeholder
JSON Server
mocki Fake JSON API
httpbin(1)
MockRest
Nacapi
Format JSON Online
A hosted REST-API ready to respond to your AJAX requests.

The modern platform for creating, sharing, and collaborating on AI prompts. Advanced version control and real-time testing.

Which is more popular?
Based on our record, ReqRes seems to be more popular. It has been mentioned 21 times since March 2021.
Website, pricing, platforms and company facts side by side.
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ReqRes
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| Website | reqres.in | diffyn.com |
| Pricing | — | |
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| Listed in |
What each product offers, as listed by its team.

Possible disadvantages
An editorial look at what each product does well and who it suits.

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Overall verdict
Why this product is good
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The Ultimate Prompt Tool for Creators – Visualize & Organize with Diffyn
How often each product is chosen within a category, 0–100% relative to the other.

As answered by people managing ReqRes and Diffyn.
Diffyn's answer:
Addresses workflow and change management on LLM prompts, provide teams with traceability and visualization of tests across multiple models, provide deeper understading into efficiency of these prompts.
Diffyn's answer:
Diffyn is the platform that specializes on both change management and multi-model analysis.
Diffyn's answer:
React, Next.js, POSTGRESQL
Diffyn's answer:
Professionals incorporating LLMs or AI tools in their workflow and wants to keep track of changes and test their prompts.
Diffyn's answer:
I started working on Diffyn when I notice that prompting has become an essential part of work across many industries. While there are version control platofrms like github, they are not designed for just prompt management are can be overkill such applications, it is also not integrated natively with various LLMs and relevant tools for users to validate ideas and visualise results properly.
Share your experience with using ReqRes and Diffyn. For example, how are they different and which one is better?
Recommendations tracked on public social media and blogs since March 2021.

Https://reqres.in/ - roughly that much in ads revenue. Would love to add a paid plan for more features, but....time. - Source: Hacker News / almost 2 years ago
Reqres.in - A Free hosted REST-API ready to respond to your AJAX requests. - Source: dev.to / over 2 years ago
As stated earlier we are using the REQ | RES API in the example, you can check it out to see all the methods it provides. Now, go to the core/internet_services/ create a dart file and name it paths.dart, this will contain the baseurl and... - Source: dev.to / over 3 years ago
Tracking Diffyn since Jun 2025.
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