Thunder Client

Executes HTTP requests (GET, POST, PUT, DELETE, PATCH, etc.) with full header/body customization and displays formatted responses (JSON, XML, HTML, plain text) in a tabbed interface. Requests are composed via a GUI form builder with separate sections for URL, headers, body, and parameters, then transmitted over the network and responses are parsed and displayed with syntax highlighting and collapsible sections for inspection.

Organizes HTTP requests into nested folder structures (collections and sub-collections) stored as local JSON files, enabling developers to group related API endpoints by domain, feature, or environment. Collections are persisted locally on disk and can be expanded/collapsed in the sidebar tree view, with each request stored as an individual item that can be executed directly from the tree without opening a separate editor.

Supports dynamic value injection into requests via template variables ({{variableName}}) that are resolved at request execution time. Variables can reference environment variables, request metadata (timestamp, random UUID, etc.), or previous response values (unclear if supported). This enables developers to generate unique request identifiers, timestamps, or other dynamic values without manual editing before each request.

Captures and displays HTTP request/response timing metrics including total request duration, DNS lookup time, connection time, and time-to-first-byte (TTFB). Metrics are shown in the response header alongside status code and content size, enabling developers to identify performance bottlenecks in API endpoints. Timing data is also recorded in request history for trend analysis.

Defines environment-specific variables (API keys, base URLs, tokens, etc.) that are substituted into requests using {{variableName}} template syntax. Variables are scoped to named environments (e.g., 'development', 'staging', 'production') and stored locally; when a request is executed, the active environment's variables are resolved and injected into the URL, headers, and body before transmission.

Executes GraphQL queries and mutations against GraphQL endpoints by accepting a GraphQL query string in the request body, sending it via HTTP POST with the appropriate Content-Type header, and parsing the JSON response to display both data and errors in a formatted view. Supports introspection queries for schema discovery and displays nested GraphQL response structures with collapsible sections.

Automatically records all executed HTTP/GraphQL requests with timestamps and response metadata in a chronological history view, allowing developers to browse past requests and re-execute them with a single click. History entries include request method, URL, status code, and response time; clicking a history entry loads the request configuration back into the editor for modification or immediate replay.

Provides a GUI-based assertion builder (described as 'Scriptless Testing') that allows developers to define validation rules for API responses without writing code. Assertions are configured via dropdown menus and form fields to check response status codes, headers, body content (JSON path matching, string contains, regex), and response time thresholds; assertions are executed automatically after each request and results are displayed with pass/fail indicators.

Exports request collections to a Git repository (local or remote) as JSON files, enabling teams to version control, share, and collaborate on API requests without a centralized cloud service. Collections are committed to Git with human-readable JSON structure; team members clone the repository and Thunder Client automatically loads collections from the Git directory, with changes pushed/pulled via standard Git workflows.

Provides a command-line interface (separate from the VS Code extension) that executes Thunder Client requests, collections, and cURL commands from the terminal or CI/CD pipelines. The CLI accepts collection files, environment variables, and request parameters as arguments and outputs results in machine-readable formats (JSON, reports); this enables automated API testing in GitHub Actions, Jenkins, GitLab CI, and other CI/CD systems without requiring the VS Code UI.

Accepts cURL command strings (from browser DevTools, documentation, or other sources) and automatically parses them into Thunder Client request format, extracting method, URL, headers, and body. The converted request is loaded into the editor for execution or modification, eliminating manual re-entry of complex curl commands and enabling developers to reuse API examples from documentation or network traces.

Automatically detects response content type (JSON, XML, HTML, plain text) and applies syntax highlighting with indentation and collapsible sections for nested structures. JSON responses are formatted with pretty-printing and can be collapsed/expanded by object or array; XML and HTML are indented and highlighted; response size and type metadata are displayed in the header. This enables developers to quickly parse and understand API responses without manual formatting.