A small disclaimer to avoid unnecessary disagreements with Postman fans :)
If you are a power user of Postman and other legacy tools like Insomnia etc, I recommend to NOT try this. Its very different and almost has a totally different take of how things should be around API work.
Dont want to play “smart ass” its just that the purpose was not to build yet another (cheaper) clone of Postman. There are enough of them out there and some of them are great as well. Ask me and I can recommend some :)
How this is actually different:
When you check the tool, the first thing you will notice is that you start from an empty page (a Voiden doc).
Its then all up to you what you want to do with this - how you want to get started, perhaps add headers, or maybe start documenting something. Its all up to you.
Then you will also notice that:
<ul>
<li>The UI is “programmable”: Everything (requests etc) is “built” with slash commands from reusable blocks (endpoints, headers, auth, params, bodies, etc.), like LEGO for APIs. Let me explain a bit: The way that this works is that every part of a request (endpoints, headers, auth, params etc) are all blocks that can be added or removed in the doc.</li>
<li>These blocks can be reused in different APIs to have ALL common elements done in one file and then change them once and it will all get updated in all the other docs (just like in code - when we add a extra logic to an imported method).</li>
</ul>
(In other API clients you mainly duplicate stuff or just use environment variables to substitute. )
<img src="https://media.daily.dev/image/upload/s--qfth57lU--/f_auto/v1774015322/ugc/content_5808de4c-93e1-4b9d-808d-4ba9d1e123e5?_a=BAMAMiWQ0" alt="Screenshot 2026-03-20 at 3.01.45 PM.png">
<ul>
<li>
Specs, tests, and docs together all live in executable plain text (Markdown).
</li>
<li>
If you are into scripting, another thing you will notice is that Pre- and post-request scripting supports JS (like everyone) but also supports Python, Shell etc.
</li>
</ul>
A few more points:
<ul>
<li>
Plugins: new functionality lives as plugins, so you install only what you need (gRPC, GraphQL, WebSockets, etc.).
</li>
<li>
Git is the source of truth: collaboration and versioning happen in Git and of course: Offline-first: no accounts, no telemetry.
</li>
</ul>
New release:
Are you using Claude or Codex agents to build your application?
<ul>
<li>We just shipped integration of Voiden skill to Claude and Codex Agents. This means that your agent can understand Voiden files, blocks, plugins etc.</li>
</ul>
If this is something that resonates, you should definitely try.
Welcome all ideas and thoughts!
repo: <a href="https://github.com/VoidenHQ/voiden" target="_blank" rel="noopener nofollow">https://github.com/VoidenHQ/voiden</a>
get the tool: <a href="https://voiden.md/download" target="_blank" rel="noopener nofollow">https://voiden.md/download</a>

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Backend Developer 

Voiden is an API client tool that takes a fundamentally different approach from Postman and similar tools. It uses a document-based, block-oriented workflow where API requests are built from reusable LEGO-like components (endpoints, headers, auth, params, bodies) via slash commands in Markdown. Blocks can be shared across multiple API docs so changes propagate everywhere, similar to code reuse. Key differentiators include: specs, tests, and docs coexisting in executable plain-text Markdown; pre/post-request scripting in JS, Python, or Shell; a plugin system for gRPC, GraphQL, WebSockets; Git as the collaboration/versioning layer; offline-first with no accounts or telemetry. A new release adds integration with Claude and Codex agents so AI agents can understand Voiden files and blocks.

We LEGO-fied API workflows so they adapt to developers, not the other way around