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Get started with Yasumu

This quickstart guide will take you from installing Yasumu to making your first API request in under 5 minutes.
1

Download and install Yasumu

Visit yasumu.dev/download and download the installer for your operating system:
  • Windows: .msi or .exe installer
  • macOS: .dmg installer
  • Linux: .AppImage, .deb, or .rpm package
Run the installer and follow the platform-specific instructions. See the installation guide for detailed steps.
2

Create your first workspace

When you launch Yasumu for the first time, you’ll be prompted to create or open a workspace.
  1. Click Create New Workspace
  2. Choose a directory for your project (or create a new folder)
  3. Give your workspace a name (e.g., “My API Project”)
  4. Click Create
Yasumu will create a yasumu directory in your project containing:
my-project/
└── yasumu/
    ├── rest/              # REST API requests
    ├── environment/       # Environment files
    ├── workspace.ysl      # Workspace metadata
    ├── smtp.ysl          # SMTP configuration
    └── yasumu-lock.json  # Dependency tracking
The workspace is just a folder structure with .ysl files. You can commit it to Git like any other code.
3

Create your first REST request

  1. In the left sidebar, click the + button next to “Requests”
  2. Select REST Request
  3. Enter a name for your request (e.g., “Get users”)
  4. Click Create
You’ll see a new request editor with:
  • Method dropdown: GET, POST, PUT, PATCH, DELETE, etc.
  • URL input: Enter your API endpoint
  • Headers tab: Add request headers
  • Body tab: Add request body (for POST/PUT/PATCH)
  • Scripts tab: Add pre/post request scripts
  • Tests tab: Add automated tests
4

Make your first API call

Let’s make a simple API call to JSONPlaceholder (a free fake REST API):
  1. Set the method to GET
  2. Enter the URL: https://jsonplaceholder.typicode.com/users
  3. Click Send
You should see a response with a list of users in the response panel below.
The request is automatically saved to yasumu/rest/get-users.ysl in your workspace directory.
5

Create an environment

Let’s create an environment to manage API base URLs and variables:
  1. Click Environments in the left sidebar
  2. Click Create Environment
  3. Name it “Development”
  4. Add a variable:
    • Name: BASE_URL
    • Value: https://jsonplaceholder.typicode.com
  5. Click Save
Now you can reference this in your requests using {{BASE_URL}}:
URL: {{BASE_URL}}/users
Create separate environments for development, staging, and production to easily switch between different API endpoints.
6

Organize with groups

As you add more requests, organize them into groups:
  1. Right-click in the sidebar
  2. Select New Group
  3. Name it (e.g., “Users API”)
  4. Drag and drop requests into the group
Groups create folders in your yasumu/rest/ directory for better organization.
7

Version control with Git

Since everything is stored as .ysl files, you can version control your API workspace:
# Initialize git if not already done
git init

# Add the yasumu directory
git add yasumu/

# Commit your API definitions
git commit -m "Add initial API requests"

# Push to remote
git push origin main
Your teammates can now clone the repo and open the workspace in Yasumu to see all your API definitions.
Don’t commit secrets! Use environment variables for sensitive data and keep them in a .env file that’s gitignored.

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What’s next?

Core concepts

Learn about workspaces, environments, and the schema language

REST API testing

Deep dive into REST API testing features

Email testing

Set up the catch-all SMTP server for email testing

Scripting

Write pre/post request scripts in TypeScript

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Common tasks

  1. Open your request
  2. Click the Headers tab
  3. Click Add Header
  4. Enter the header name and value
  5. Click Save
You can use environment variables in headers:
Authorization: Bearer {{API_TOKEN}}
  1. Set the method to POST
  2. Go to the Body tab
  3. Select JSON from the content type dropdown
  4. Enter your JSON payload:
{
  "name": "John Doe",
  "email": "[email protected]"
}
  1. Click Send
  1. Click the environment dropdown in the top toolbar
  2. Select the environment you want to activate
  3. All requests will now use variables from that environment
Use environment variables for auth tokens:
  1. Create an environment variable API_KEY or AUTH_TOKEN
  2. In your request headers, add: 
    Authorization: Bearer {{API_KEY}}
  3. Or use a pre-request script to generate dynamic tokens: 
    // onRequest script
const token = await generateToken();
req.headers.set('Authorization', `Bearer ${token}`);
  1. Go to Email in the sidebar
  2. Click Start SMTP Server
  3. Note the SMTP port (usually 1025)
  4. Configure your app to send emails to localhost:1025
  5. Trigger your email workflow
  6. View captured emails in Yasumu’s email inbox
See the email testing guide for detailed instructions.

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Get help

Documentation

Browse the full documentation

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