kurlo

Kurlo

A fast, local-first desktop API client. No accounts, no cloud sync, no telemetry — just you and your APIs.

Built with Go, Svelte 5, and Wails.

Download

Grab the latest build from the releases page.

Every release ships SHA256 checksums and minisign signatures, and the in-app updater refuses any binary that fails either check.

The command line (kurlo run for CI, kurlo mcp for AI agents) is also on npm as @kurlo/cli, with prebuilt binaries for macOS, Linux and Windows on x64 and arm64. It does not need the desktop app:

npx -y @kurlo/cli --version

Guides, the scripting reference, and the YAML workspace format live in the documentation site.

Features

Requests

• All HTTP methods: GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS

• Query params, headers, body (JSON, form-data, x-www-form-urlencoded, raw text/XML/HTML, binary file)

• cURL import — paste a curl command into the URL field, it parses automatically

• Bulk edit for params, headers and form fields — switch the table to a key: value text area and back

• GraphQL, Server-Sent Events, WebSocket, Socket.IO, gRPC, and MCP request types — an MCP call discovers the server's tools, resources and prompts, seeds the arguments from the tool's schema, and shows the raw JSON-RPC exchange

• Postman, Insomnia, Bruno/OpenCollection, OpenAPI/Swagger, HAR, cURL, and all-data backup import paths

• OpenAPI/Swagger imports from a link as well as a file — paste the spec URL and Kurlo fetches it and builds the collection

• Postman, OpenAPI, OpenCollection, and all-data backup export paths

Authentication

• Bearer Token

• Basic Auth

• Digest Auth — MD5, SHA-256 and SHA-512-256 plus their -sess variants, with qop=auth and auth-int

• API Key — in header or query string

• OAuth 2.0 — Client Credentials, Authorization Code (with PKCE), Password, and Device Code grants; loopback browser sign-in, refresh tokens, and automatic token refresh before each send

• AWS Signature v4

• Client certificates (mutual TLS), per request or inherited from a collection

• Per-request and collection defaults with inheritance

Scripting — pre-request and test scripts in sandboxed JavaScript, with legacy Tengo support:

// pre-request: inject a header
pm.request.headers.set("X-Client", "kurlo")

// pre-request: rewrite and sign the body
pm.request.body.update(JSON.stringify({ ...pm.request.body.json(), nonce: pm.crypto.randomHex(8) }))

// test: assert status and shape
pm.test("status is 200", () => pm.response.to.have.status(200))
pm.test("has an id", () => pm.response.to.have.jsonSchema({ type: "object", required: ["id"] }))

require resolves bundled stand-ins for lodash, ajv, tv4, uuid, crypto-js, and chai, so imported Postman scripts keep working. pm.sendRequest makes an HTTP call from a script, and pm.execution.skipRequest() skips the send.

Environments & Variables

• Multiple environments per workspace, switch with one click

• Matrix view — every variable as a row, every environment as a column, edited in place

• {{variable}} template syntax in URLs, headers, params, body, auth fields

• Set variables from test scripts (pm.variables.set, pm.environment.set)

• Manual-save and autosave modes both cover request and environment edits

Workspaces & Collections

• Multiple workspaces for separate projects or clients

• Collections with nested folder hierarchy and empty-folder preservation

• Drag-and-drop organisation

• Request history — every send on its own page, request and stored response side by side, reopenable in the editor (14-day retention, 1000 entries)

• Collection runner — sequential or parallel, data files, iterations, an HTML report, and the last run of every collection kept

• Git-backed YAML workspaces with diagnostics, conflict helpers, and local-only secrets

• CLI runner — npx -y @kurlo/cli run ./workspace --env CI executes requests and their test scripts for CI, with data-driven iterations (--data), pretty/JSON/JUnit reporters, variable export, and a non-zero exit code on failure

AI agents (MCP server) — the Kurlo binary is also a Model Context Protocol server, so Claude Code, Codex, Cursor, Claude Desktop or any other MCP client can list your collections and environments, run saved requests and whole collections with their auth, scripts and tests, and send one-off calls with your {{variables}}. It can also keep the workspace up to date: add and change requests with their pm.* tests, save responses as examples and set environment variables, in the same YAML the app writes, never storing a secret. It reads the last request you sent from the app, so "why did that fail?" needs no copying. Secret values are sent to the API but masked as [secret] in everything the model sees, and environments you mark protected are off limits. One command sets up every client on the machine:

npx -y @kurlo/cli mcp install --env Staging

Add --project to write a repository's shared .mcp.json and .cursor/mcp.json instead, so the whole team gets the server by cloning. Manual setup, the tools and the flags are covered in the MCP server guide.

Response examples — save any response as a named example on its request: the status, headers and body it came back with, alongside the request that produced it. Secrets are redacted on capture, a clean body is stored byte for byte, and examples ride along through Postman, OpenCollection, HAR and OpenAPI imports and exports. A response can be diffed against an example instead of against the previous send.

Cookies — a per-workspace cookie jar with a per-domain editor, disableable per request.

• Cookie sync: pair Kurlo with the in-repo browser extension (apps/desktop/extension, Chromium + Firefox) and the session you already have in the browser is the session Kurlo sends with. A loopback-only bridge that stays off until you turn it on, an approval you give in Kurlo by matching a six-digit code, and a per-domain allowlist enforced on both sides. Cookies travel one way: browser into Kurlo.

Mock server — serve a collection's saved examples over HTTP on a local port, so a client can be built against an endpoint that does not exist yet. Routing is by method and the example's path template (/orders/:id), a recorded query narrows which example answers, and a live log shows what the client asked for and which example replied. Loopback only; CORS preflight is answered for any origin.

Response viewer

• Syntax-highlighted body with line numbers

• Paginated rendering for large responses (512 KB pages, once a response exceeds 10 MB)

• Full-text search with match navigation

• Save response to file, copy to clipboard

• Headers table, test results, script logs — all in one panel

• Preview tab for HTML, images and PDFs; binary bodies are detected rather than rendered as mojibake

• Diff against the previous response or a saved example

• Timeline with connection details and the request as it went on the wire, secrets masked, one block per redirect hop

• Realtime panels for SSE, WebSocket, Socket.IO, and gRPC responses

Code generation — copy the current request as a runnable snippet in one of 14 targets: cURL, HTTPie, JavaScript fetch, Node.js fetch, Axios, Python requests, Go net/http, Java OkHttp, C# HttpClient, PHP cURL, Ruby Net::HTTP, Swift URLSession, Kotlin OkHttp, and Rust reqwest. Secret variables stay as {{name}} placeholders.

Browser request emulation — send with a browser's rules instead of a client's: an Origin header, CORS preflight and response checks, and Content Security Policy enforcement, so a request can reproduce what the browser will do before the frontend is written.

Settings per request: HTTP version (auto / 1.1 / 2), SSL verification, redirect policy (follow, preserve method, preserve auth), cookie jar, timeout, proxy, URL encoding.

Keyboard-first: all actions have configurable shortcuts. A command palette (Cmd/Ctrl K) finds requests and runs commands, quick send (Cmd/Ctrl Enter), focus the URL (Cmd/Ctrl L), tab switching (Cmd/Ctrl 1–8, with 9 for the last tab). Kurlo shows Cmd on macOS and Ctrl on Windows and Linux.

Dark and light themes, with multiple built-in variations.

Local-first storage — the local Kurlo profile and its secrets are encrypted at rest with AES-256-GCM. The key is stored in the OS credential store when available and also kept as a 0600 recovery file in Kurlo's app-data directory. Git-backed workspace YAML is intentionally human-readable; secret values are replaced with local placeholders.

Building from source

Prerequisites

• Go 1.25+

• Node.js 22.12+

• Wails v2 — go install github.com/wailsapp/wails/v2/cmd/wails@latest

• macOS: Xcode Command Line Tools

• Windows: NSIS (for installer builds) and Windows SDK (for MSIX packaging/signing tools)

• Linux: libgtk-3-dev, libwebkit2gtk-4.1-dev