API testing used to be synonymous with Postman. Then Postman changed its pricing and syncing model, and developers started looking around. What they found was a surprisingly healthy ecosystem of alternatives — some open source, some lightweight, some designed specifically to avoid the cloud-sync dependencies that made Postman feel heavier than it needed to be.
In 2025, the best free API testing tool depends on what you actually need: a full-featured desktop app, something embedded in your editor, a shareable web interface, or a scriptable CLI. This guide covers all of those bases.
Quick Comparison Table
| Tool | Type | Free Tier | Collaboration | Collections | Scripting | Offline |
|---|---|---|---|---|---|---|
| Postman | Desktop/Web | Yes (limited) | Yes | Yes | Yes | Partial |
| Insomnia | Desktop | Yes (local only) | Paid | Yes | Yes | Yes |
| Bruno | Desktop | Fully free | Via Git | Yes | Yes | Yes |
| Hoppscotch | Web/Self-host | Yes | Yes (limited) | Yes | Yes | Web only |
| HTTPie | Desktop/CLI | Free (CLI) | No | No | No | Yes |
| Thunder Client | VS Code ext | Yes | No | Yes | Limited | Yes |
| REST Client | VS Code ext | Yes | Via files | Via files | No | Yes |
| httpx | CLI/Python | Yes | No | No | Yes (Python) | Yes |
| curl | CLI | Yes | No | No | Shell | Yes |
| Paw | Desktop (Mac) | Trial | No | Yes | Yes | Yes |
1. Postman
Postman remains the most feature-complete API testing platform available, and its free tier is still genuinely useful for individual developers. You get unlimited API calls, collection management, environment variables, pre-request scripts, test scripts, and the Postman console for debugging.
What's changed
The friction points are around collaboration and storage. Free accounts are limited to 3 users on a team, and collection sync happens via Postman's cloud — your collections live on their servers, not locally. This is a dealbreaker for some teams with data security requirements.
What still makes it worth using
The documentation, learning resources, and ecosystem around Postman are unmatched. If you work with public APIs that provide Postman collections, they drop directly into your workspace. The API documentation generation feature is also strong, and Postman Flows (visual API chaining) is a genuinely useful feature not found in most alternatives.
Best for: Individual developers and small teams who want the richest feature set and are comfortable with cloud sync.
2. Insomnia
Insomnia (by Kong) underwent a controversial change in 2023 when it added mandatory cloud login for sync. The community's reaction pushed the maintainers to restore a "local vault" option — meaning you can now use Insomnia fully offline without an account.
The interface is clean and fast. Collections are called "request collections," environments are handled elegantly, and the plugin system allows extending functionality without bloat. GraphQL support is first-class, which matters if your team works with GraphQL APIs heavily.
Pricing: Free for local use. Cloud sync and team features require a paid plan ($12/month per user).
Best for: Developers who want a clean Postman alternative that supports GraphQL and works fully offline.
3. Bruno
Bruno has earned a devoted following by doing something simple: storing your API collections as files in your filesystem using a plain-text format (.bru files). There's no cloud sync, no account required, and your collections live in your repo alongside your code.
This "Git-native" approach means collaboration happens through the same version control workflow you already use. Diff your API collections, review changes in PRs, roll back to previous versions — all using standard Git tooling.
Features:
- Completely open source (MIT license)
- Offline-first, no cloud dependency
- Supports pre-request scripts and test scripts (JavaScript)
- Environment variables with local override support
- Active development and growing plugin ecosystem
Best for: Developers and teams who want to version-control their API collections alongside their code without any cloud dependency.
4. Hoppscotch
Hoppscotch is a web-based API client that runs entirely in the browser. You open hoppscotch.io, make requests, and organize them into collections — no installation required. For quick, one-off API exploration from any machine, nothing is faster to start with.
It supports REST, GraphQL, WebSocket, SSE, Socket.IO, and MQTT — a wider protocol range than most desktop clients. For teams with data privacy concerns, the self-hosted option lets you run the entire platform on your own infrastructure.
Limitations: The web-based model means you can't make requests to localhost APIs without installing their browser extension or the self-hosted version. This is a meaningful friction point for local development.
Pricing: Free for the hosted version. Self-hosted is free. A team plan with sync features is available at $12/month per user.
Best for: Quick API exploration without installation, or teams who can self-host and want a polished web UI.
5. HTTPie
HTTPie comes in two forms: a powerful CLI tool and a cross-platform desktop app. The CLI version is what many developers reach for when curl feels too verbose — HTTPie's syntax is designed for human readability.
# HTTPie vs curl for a POST request
http POST api.example.com/users name="Alice" email="alice@example.com"
# Equivalent curl command
curl -X POST -H "Content-Type: application/json" \
-d '{"name":"Alice","email":"alice@example.com"}' \
api.example.com/users
The desktop app (HTTPie for Web and Desktop) offers a GUI around the same principle: readable, structured, uncluttered. It handles sessions, authentication, and request chaining cleanly.
Pricing: CLI is free and open source. Desktop app has a free tier with limited sync; paid plans start at $4/month.
Best for: Developers who spend time in the terminal and want a cleaner syntax than curl, or who prefer a minimal desktop GUI.
6. Thunder Client (VS Code Extension)
Thunder Client lives inside VS Code as a sidebar panel. You send requests without switching applications, which sounds minor but reduces context-switching significantly during development. Collections, environments, and basic test assertions are all supported directly in the extension.
The "local storage" mode (introduced after user feedback) stores everything as JSON files in your project directory, making it Git-compatible similar to Bruno.
Best for: VS Code users who want API testing without leaving the editor, especially during active development cycles.
7. REST Client (VS Code Extension)
REST Client takes a different philosophy: instead of a GUI, you write HTTP requests as .http or .rest files using a simple plain-text format, then click "Send Request" above each one. Responses appear in a side panel.
### Create user
POST https://api.example.com/users
Content-Type: application/json
{
"name": "Alice",
"email": "alice@example.com"
}
These files are plain text, diff cleanly, live in your repo, and serve as implicit API documentation. For teams who think in terms of "API contracts as files," this approach is more natural than GUI-based tools.
Best for: Developers who want their HTTP requests version-controlled as human-readable files and prefer a code-first approach.
8. httpx (Python)
httpx is a Python HTTP client library, not a GUI tool — but for developers who write Python scripts, it's the modern replacement for the requests library, with async support, HTTP/2, and a built-in command-line client:
python -m httpx https://api.example.com/data -m POST \
--json '{"key": "value"}'
When your API testing needs to be scripted, automated, or integrated into Python code, httpx is the right tool. It's not a Postman replacement for interactive exploration, but for automated test scripts and CI integration it's excellent.
Best for: Python developers who need programmatic API testing that integrates directly with test suites.
9. curl
curl is the universal baseline. It's installed on virtually every Unix-like system, it supports every protocol you'll encounter, and every API's documentation includes curl examples. The syntax is verbose but it's predictable and scriptable.
For one-off requests and shell script automation, nothing beats curl for availability and portability. The limitations are in readability and the lack of session management — for interactive testing of complex APIs, you'll want a GUI tool.
Best for: Quick one-off requests, shell script automation, and situations where you need something that's definitely available on any machine.
10. Paw (now RapidAPI for Mac)
Paw is a native Mac app for API testing that has been acquired and rebranded as part of RapidAPI. The native Mac implementation means excellent performance, system keychain integration, and a polished macOS-native interface. It supports code generation (export requests as curl, Python, JavaScript, etc.) and has a strong extension ecosystem.
Pricing: A free trial is available; the full version requires a subscription. The acquisition by RapidAPI has introduced some pricing uncertainty.
Best for: Mac-only teams who want native performance and deep macOS integration and are willing to pay for it.
Choosing the Right Tool
The question of cloud sync is what drives most people away from Postman today. If that's your concern, Bruno and REST Client are the purest "local-first" options. Thunder Client with local storage and Insomnia with local vault also solve this.
For team collaboration without a paid plan, Bruno's Git-native approach is elegant: your team already knows how to collaborate using Git, and Bruno's .bru files work within that workflow naturally.
For protocol breadth beyond REST/HTTP, Hoppscotch supports the widest range (WebSocket, GraphQL, SSE, MQTT) in a free tier.
For CLI-first developers, HTTPie dramatically improves on curl's ergonomics while staying in the terminal.
Which Should You Choose?
- Switching from Postman (keep the workflow): Insomnia or Bruno
- Want Git-native collections: Bruno
- VS Code user, don't want to leave the editor: Thunder Client
- Code-first, files in the repo: REST Client
- Web-based, no install: Hoppscotch
- Terminal user: HTTPie
- Python developer: httpx
- Mac-native performance: Paw (with caveats on pricing)
All of these tools are catalogued at devplaybook.cc with direct links and additional context. The era of "just use Postman" is over — the alternatives have caught up, and several of them handle specific use cases better than Postman ever did.
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