⚡ FastClient – Lightweight REST API Client

A tiny, fast REST/HTTP API client for VS Code and all its forks. Send requests, organise them in collections stored as plain JSON files in your repo, switch environments, and import/export cURL — without leaving the editor and without a heavyweight extension.

Features

• Request editor – method, URL, query params (synced with the URL), headers, body (JSON, form-urlencoded, multipart with file uploads, raw text) and auth (Basic, Bearer). Request and response sit side by side (or stacked — toggle in the header), with the active environment, Copy as cURL and Import cURL one click away.
• Variable check before sending – the line under the URL shows the resolved URL and flags {{variables}} the active environment does not define; one click on Add to <env>.local.json asks for the value and stores it in a git-ignored local file.
• Response viewer – status, time, size, headers, cookies, pretty-printed and highlighted JSON, a JSONPath filter, a Test results tab and a Table view for JSON arrays (sortable, searchable, copy as CSV).
• Environment card – the sidebar shows the active environment and its variables (secrets masked, captured values marked) at the top.
• Collections as files – requests are saved as readable JSON under .fastclient/ in your workspace, so they can be committed, reviewed and shared with git. No account, no cloud sync.
• Organisable collections – drag requests into collections and reorder requests or collections in the sidebar. Drag a collection onto another collection to nest it.
• Environments – {{baseUrl}}-style variables, nested variables, {{$env.NAME}} (process env) and dynamic variables. Secrets go into environments/<name>.local.json, which is git-ignored automatically.
• Tests and chaining – declarative assertions on status, headers, JSON paths and response time, plus capturing response values into {{variables}}. Run a whole folder or collection and see pass/fail per request.
• cURL import / export – paste a cURL command (bash, Windows cmd and PowerShell styles) or copy any request as cURL.
• Postman & OpenAPI import / export – import Postman collections (v2.0 / v2.1) and environments, OpenAPI 3.x and Swagger 2.0 (JSON or YAML); export any collection as a Postman v2.1 collection or an OpenAPI 3.0 document.
• History – recent requests in the sidebar (configurable limit).
• Networking – follows redirects, timeout, cancel, gzip / deflate / brotli decoding, optional acceptance of self-signed certificates (like curl -k).

Why it's light

• Zero runtime dependencies – the HTTP client is built on Node's own http/https modules.
• One small bundle – the whole extension is a single minified file; the UI is plain DOM with no framework. The VSIX is well under 150 KB.
• Lazy activation – nothing runs until you open the FastClient view or run a command.
• No telemetry, no login, no background processes.

Compatibility

Requires an engine compatible with VS Code 1.74+ and uses only stable APIs (no proposed APIs), so it works in:

• Visual Studio Code and VS Code Insiders
• Cursor
• Windsurf
• VSCodium (install from Open VSX or the .vsix)
• code-server / browser-hosted VS Code (server side)
• Remote – SSH, WSL and Dev Containers (the extension runs on the workspace side, so requests reach hosts such as localhost on the remote machine)

Getting started

1. Click the ⚡ FastClient icon in the activity bar.
2. Create a request with New Request (Ctrl+Alt+N) or New Request from cURL (Ctrl+Shift+I).
3. Press Ctrl+Enter to send and Ctrl+S to save it into a collection.

In the Collections tree, drag a request onto a collection to move it there. Drop an item above or below a sibling to change its order; drop a collection into another collection to nest it.

Editor layout

• Header – breadcrumb (collection › request, with an Unsaved badge), the environment button (click to switch), Copy as cURL, Import cURL and the layout switch: side by side (default) or stacked. Narrow editors always stack. Drag the divider to resize; double-click it to reset.
• URL bar – method, URL with highlighted {{variables}}, Send (the arrow next to it opens Save, Save as…, Copy as cURL and Import from cURL) and Save (with a dot while there are unsaved changes).
• Resolved line – under the URL: the URL as it will be sent and a warning for undefined variables. Click a variable or Add {{name}} to <env>.local.json to enter its value.
• Request tabs – Params, Headers, Body, Auth, Tests.
• Response – status, time, size and a test summary chip; tabs Body, Headers, Cookies and Test results.

Headers, params and form fields

Headers, Params and Form fields have a Table / Text switch:

• Table – one row per entry. Enter moves from name to value and on to the next row, Ctrl+Shift+Backspace deletes the row, Alt+↑ / Alt+↓ reorders rows. Repeated header names are flagged as duplicate.
• Text (bulk edit) – one Key: Value per line; start a line with // to disable it (Ctrl+/ toggles).
• Smart paste – paste DevTools "Copy request headers", a raw HTTP request, curl … -H '…', a URL or query string, or a=1&b=2 and the entries are merged in automatically.
• Autocomplete – header names and typical values, plus {{variables}} after {{. Ctrl+Space shows all suggestions.
• + Common – a checklist of common headers (Content-Type, Accept, Authorization, Cache-Control, …) with a filter.
• Presets – save the current headers as a preset and apply them to any request.
• Auto-generated headers – shown greyed out: Authorization (from Auth), Content-Type (from body type), Content-Length, User-Agent and Accept. A header you set with the same name overrides the auto one.

File uploads (multipart)

Choose Multipart as the body type. Each field is Text or File:

• Choose… opens the file dialog. Files inside the workspace are stored relative to the workspace folder (portable); files elsewhere are stored with an absolute path.
• Each file row shows the file name and size, or File not found / No file chosen; uploads over 50 MB are marked large upload.
• Files are streamed from disk when the request is sent (never loaded into memory).

Table view

For JSON responses, choose Table next to Pretty / Raw:

• Shows an array of objects found at the root, at a top-level property or one level deeper (e.g. $.data, $.items).
• Works on the JSONPath filter result too.
• Columns are the union of keys of the first 200 rows; nested objects and arrays are shown as compact JSON.
• Click a column header to sort; search all columns or one column.
• At most 1,000 rows are rendered; sorting, search and CSV export still use every row.

Tests and running collections

Open the Tests tab of a request. Tests are plain data saved in the request's JSON file — nothing is ever executed, so they are safe in untrusted workspaces.

"tests": [
  { "type": "status", "equals": 200 },
  { "type": "json", "path": "$.data.id", "type_is": "number" },
  { "type": "header", "header": "content-type", "contains": "json" },
  { "type": "time", "lt": 500 },
  { "type": "bodyContains", "value": "ok" }
],
"extract": [
  { "var": "token", "from": "json", "path": "$.data.jwt" }
]

• Add test from response proposes tests (status, typed top-level fields) and token-like fields to capture.
• Capture to variable (extract) stores a JSON value or header into a runtime {{variable}} that overrides the active environment. Runtime variables are never written to disk.
• Run folder / collection: use the ▶ button on a folder in the sidebar. Requests run one at a time in sidebar order, so a login request can feed the next ones. Results appear in the Run Results page.

Sidebar

• Quick access: starred requests (☆ on any request row) and recently opened ones, per workspace.
• Quick start: shown until you send the first request.
• Environment status: the active environment and a ⚠ count of undefined {{variables}}. Expand to see which requests use them and add a value.
• Overview: requests sent today with a 7-day trend, average / p95 response time, errors, a response-time chart and the last collection run.
• Tips at the bottom; use ‹ › to browse.

Run results

Running a folder or collection opens the Run Results page:

• Header: collection, environment, start time, duration and progress; Stop while running, Re-run failed / Re-run all afterwards.
• Summary: pass ring, passed / failed / skipped counts, average and total request time.
• Requests: method, name, resolved URL, HTTP status, time, size and tests passed. Expand a row to see every test with expected / actual values, and the response.
• Export as JSON, JUnit XML or a self-contained HTML report.

Import and export

Import — New Request ▾ → Import Postman / OpenAPI…, the FastClient: Import Postman / OpenAPI… command, or right-click a .json / .yaml file in the Explorer.

Importing into an existing collection asks what to do: Update, Replace or Add as copies.

Export — the export button on a collection row or FastClient: Export Collection as Postman / OpenAPI…:

• Postman Collection v2.1 — folders, requests, auth and test scripts.
• OpenAPI 3.0 (YAML or JSON) — one operation per request, folders as tags, parameters, request bodies and security schemes.

Keyboard shortcuts

All commands are also available from the Command Palette under FastClient:.

Settings

License

MIT © 2026 Putra Adi Jaya