Wallaby.js: JavaScript and TypeScript Test Runner
Wallaby.js helps software teams manage testing by providing immediate feedback. It is designed for developers practicing test-driven development (TDD) and those working with large codebases.
At a glance
- Category
- Software Development
- Best for
- Software development companies, JavaScript developers, TypeScript developers, Teams using TDD
- Pricing
- A free trial is available. Commercial licenses are offered as personal or company seat licenses, with volume discounts for 10 or more users. Free licenses are available for non-commercial open source projects.
- Key use cases
- Test-Driven Development (TDD), Bug Debugging, Managing Test Coverage, AI-Assisted Coding
- Integrations
- VS Code, JetBrains IDEs, Visual Studio, Sublime Text, Jest
- Official website
- wallabyjs.com
Wallaby.js is a test runner for JavaScript and TypeScript that executes tests as a developer types, reducing the need for manual triggers or save actions. It functions as a plugin for existing IDEs, displaying results and code coverage indicators in the editor gutter.
The tool is designed for software engineers who want to shorten the feedback loop. By calculating and running the minimum set of tests affected by a change, it supports a faster iteration process compared to traditional watch modes.
Additional features include a Time Travel Debugger and runtime value inspection. It also supports AI agents by providing runtime context, such as execution paths and dependencies, through an MCP server.
Buyers should confirm that their specific IDE and testing framework are supported, as the tool integrates into existing environments.
Key Features
Executes tests as you type and streams results directly next to the relevant lines of code.
Supports moving forward and backward through code execution to help identify the conditions that led to a bug.
Provides gutter indicators in the editor to show which lines of code are fully, partially, or not covered by tests.
Provides live runtime values, execution paths, and dependency graphs to AI agents such as Copilot, Cursor, and Claude Code.
Visualizes logged runtime data as structured, expandable graphs to help inspect nested objects.
Displays the execution history of a test in a single logical view to reduce the need to jump between multiple files.
Use Cases
Supports a TDD workflow by providing immediate feedback as code is written.
Utilizing the Time Travel Debugger and runtime value inspection to identify the cause of failures.
Identifying uncovered code regions through editor indicators to guide the creation of new tests.
Providing AI agents with runtime context to help them analyze and debug code.
Best For
Integrations
Pricing
A free trial is available. Commercial licenses are offered as personal or company seat licenses, with volume discounts for 10 or more users. Free licenses are available for non-commercial open source projects.
FAQ
Wallaby.js is a JavaScript and TypeScript test runner that executes tests as you type and displays results and coverage directly in the code editor.
It is available as a plugin for VS Code, JetBrains IDEs, Visual Studio, and Sublime Text.
Wallaby provides an MCP server and tools that give AI agents access to live runtime values, execution paths, and code coverage.
A free trial is available, and free licenses are provided for contributors to non-commercial open source projects.
Source category: Software Development
Source subcategory: Test Automation
