Introduction
A modern, free, and open-source API laboratory for designing, testing, and debugging API workflows.
Welcome to Yasumu
Yasumu is a modern, free, and open-source API laboratory for designing, testing, and debugging API workflows. Built for developer productivity, speed, and freedom — without vendor lock-in.
Beta Software
Yasumu is actively under development. You may encounter unfinished features, bugs, or inconsistent behavior as we rapidly prototype and iterate. We welcome your feedback and contributions!
Why Yasumu?
Unlike traditional API clients that store data in hidden databases or require cloud accounts, Yasumu operates like an IDE for your APIs. Your configurations live directly in your project folder, making collaboration and version control seamless.
It feels like the tools you already know, but with the flexibility to handle complex, experimental workflows directly in your file system.
Key Features
- 💾 Git-Native Workflows — Save collections as human-readable
.yslfiles. Version control your API tests alongside your code — no more syncing conflicts. - ⚡ Native Performance — Engineered with Rust and Tauri for a lightweight footprint and instant startup times.
- 🤖 Deno-Powered Scripting — Write pre-request and automation scripts using a built-in, secure TypeScript/JavaScript runtime.
- 🌐 Universal Protocol Support — A unified interface for REST, SMTP, and (soon) WebSockets and GraphQL.
- 🎨 Customizable Themes — Choose from a variety of built-in color themes to personalize your workspace.
- 💻 Command Line Interface — Execute
.yslfiles directly from the terminal for automation and CI/CD workflows. - 🔓 Truly Open Source — No paywalls, no "pro" features hidden behind cloud subscriptions, and no mandatory login.
Protocol Support
Yasumu is evolving to become a protocol-agnostic powerhouse.
| Protocol | Status | Notes |
|---|---|---|
| REST API | ✅ Ready | Full HTTP/HTTPS request support |
| Catch-all SMTP | ✅ Ready | Integrated local email server for testing |
| GraphQL | 🚧 Soon | In development |
| WebSocket | 🚧 Soon | In development |
| Server-Sent Events | 🚧 Soon | In development |
| Socket.IO | 🚧 Soon | In development |
| Plugins API | 🚧 Soon | In development |
Concepts & Workflow
Yasumu acts as an IDE for your API interactions. Unlike tools that hide data in proprietary databases or cloud silos, Yasumu lives in your repo.
Project-Based Workspaces
When you initialize Yasumu in a project, it creates a yasumu
directory. Your definitions, tests, and workflows are stored here
using the Yasumu Schema Language (.ysl) — a custom format designed
for readability and clean git diffs.
Collaboration via Git
- Commit & Push: Treat your API collections as code.
- Review:
.yslfiles are text-based, making Pull Request reviews easy. - Sync: Teammates simply pull the branch to get the latest API workflows.
- Secure: Sensitive secrets are managed via local environment variables, never committed to version control.
Hybrid Runtime
The core system runs on Tauri (Rust) for OS-level operations,
while logic and scripting utilize a custom embedded deno_runtime,
giving you a modern TypeScript environment for automation.
Quick Start
Tech Stack
Yasumu is built on a modern, performant stack:
- Frontend: Next.js with React
- Desktop Shell: Tauri (Rust)
- Scripting Engine: Embedded
deno_runtime - Platforms: Windows, Linux, macOS
Project Philosophy
- Open Source by Default — Transparency builds trust. The entire codebase is available on GitHub.
- Zero Vendor Lock-in — Your data belongs to you, stored in readable files on your disk.
- Developer Experience First — Fast, beautiful, and keyboard-friendly.
- No Artificial Paywalls — All features are free to use.
- Sustainability — Built for long-term maintainability over hype.
License
Yasumu is developed by Neplex and is licensed under the AGPL-3.0 license.