HTTP Status Codes for API Developers: Choosing the Right One
The HTTP status codes that matter when you design or debug an API — 200 vs 201 vs 204, 400 vs 422, 401 vs 403, 404 vs 410, 429, and 502 vs 503 vs 504 — with guidance on when to use each.
API Development
Voyager
One API client for fourteen protocols — local-first by default.
Voyager is a modular API development platform for building, organizing, and running requests across fourteen protocols — REST, GraphQL, SOAP, WebSocket, and more. It's local-first by default, so your requests and collections stay on your device, with optional cloud sync when you want it across machines.
- Free
- No account required
- Web · VS Code extension
Headers
- Authorization
- Bearer {{token}}
- Accept
- application/json
200 OK
{ "id": 42, "name": "Ada Lovelace", "email": "ada@example.com", "role": "admin", "active": true }
Available in: Web · VS Code
Query
query GetUser($id: ID!) {
user(id: $id) { name email }
}200 OK
{ "data": { "user": { "name": "Ada Lovelace", "email": "ada@example.com" } } }
Available in: Web · VS Code
Connected
- •System:
Connected to wss://realtime.example.com/orders - ↑Sent:
{"type":"subscribe","channel":"orders"} - ↓Received:
{"type":"ack","channel":"orders"} - ↓Received:
{"order":1042,"status":"paid"}
Available in: Web · VS Code
Streaming
- ↓Received:
{"step":"install","status":"done"}event: build · id: 17 - ↓Received:
{"step":"test","status":"passed"}event: build · id: 18 - ↓Received:
{"step":"deploy","status":"running"}event: build · id: 19
Available in: Web · VS Code
Subscribed
- •System:
Subscribed to sensors/# (QoS 1) - ↓Received:
21.4sensors/lab/temp - ↓Received:
48sensors/lab/humidity - ↑Sent:
{"fan":"on"}devices/lab/fan
Available in: Web · VS Code
Message
{ "id": "42" }
OK
{ "name": "Ada Lovelace", "plan": "PLAN_TEAM" }
Available in: VS Code extension
Why it exists
Why use Voyager?
- protocols
- 14
- import formats
- 6
- code-gen languages
- 5
The problem
A modern backend rarely speaks just REST. Testing one often means a REST client, a separate WebSocket tool, an MQTT client, and a database console — four sets of saved requests, four places for environment variables, and an account wall on most of them.
How Voyager helps
Voyager puts every protocol behind one request builder, with shared collections, environments, history, and scripts. It works without signing up and stores your workspace locally; an optional free account adds sync, sharing, and teams.
Protocols
Fourteen protocols, honestly labelled
Every protocol is available in the VS Code extension. The web app runs twelve — seven directly in the browser, and five through Voyager's relay when you're signed in, since browsers can't open raw sockets.
Request / Response
- REST / HTTPWeb · VS Code
- GraphQLWeb · VS Code
- SOAPWeb · VS Code
Streaming
- WebSocketWeb · VS Code
- Socket.IOWeb · VS Code
- Server-Sent EventsWeb · VS Code
- gRPCVS Code
IoT
- MQTTWeb · VS Code
File transfer & email
- FTP / FTPSWeb (relay) · VS Code
- SFTPWeb (relay) · VS Code
- SMTPWeb (relay) · VS Code
Raw sockets
- TCPWeb (relay) · VS Code
- UDPWeb (relay) · VS Code
Database
- PostgreSQLVS Code
Code generation
Turn any request into code
Once a request works in Voyager, export it as a ready-to-paste snippet for the language your app is written in — cURL, JavaScript, Node.js, Python, or Java.
Paste works the other way too: drop a cURL command into Voyager and it becomes a runnable request.
curl --request POST \ --url 'https://api.example.com/v1/orders' \ --header 'Authorization: Bearer eyJhbGciOi…' \ --header 'Content-Type: application/json' \ --data '{"sku":"VOY-001","quantity":2}'
const response = await fetch("https://api.example.com/v1/orders", { method: "POST", headers: { "Authorization": "Bearer eyJhbGciOi…", "Content-Type": "application/json", }, body: "{\"sku\":\"VOY-001\",\"quantity\":2}", });
import axios from 'axios'; const response = await axios.request({ method: "POST", url: "https://api.example.com/v1/orders", headers: { "Authorization": "Bearer eyJhbGciOi…", "Content-Type": "application/json", }, data: "{\"sku\":\"VOY-001\",\"quantity\":2}", });
import requests response = requests.request( "POST", "https://api.example.com/v1/orders", headers={ "Authorization": "Bearer eyJhbGciOi…", "Content-Type": "application/json", }, data="{\"sku\":\"VOY-001\",\"quantity\":2}", )
HttpClient client = HttpClient.newHttpClient(); HttpRequest request = HttpRequest.newBuilder() .uri(URI.create("https://api.example.com/v1/orders")) .header("Authorization", "Bearer eyJhbGciOi…") .header("Content-Type", "application/json") .method("POST", HttpRequest.BodyPublishers.ofString("{\"sku\":\"VOY-001\",\"quantity\":2}")) .build();
Features
Everything Voyager can do
Grouped by the job you're doing. Links open that feature in the product, or its documentation.
A request builder that speaks every protocol
One interface for request/response, streaming, IoT, file transfer, email, raw sockets, and SQL.
-
Full request builder
Methods, params, headers, and bodies — raw JSON/XML/HTML/JavaScript/text with beautify, form data, or URL-encoded.
-
Authentication
Bearer token, Basic auth, API key (header or query), and OAuth 2.0 client credentials.
-
Response viewer
Pretty, raw, and preview modes; headers and parsed cookies in their own tabs, with search; status, time, and size on every response.
-
Streaming timelines
WebSocket frames, Socket.IO events, SSE messages, and MQTT topics in a live message log.
Collections, environments, and history
Structure that mirrors your API, and variables that follow you between environments.
-
Collections & nested folders
Mirror your API's resource structure, with multiple workspaces for separate projects.
-
Environments
Switch environments from the top bar and use {{variable}} substitution in URLs, headers, bodies, and protocol settings. Secret values stay hidden from viewers when shared.
-
Request history
Every request you send is logged with method, status, and timing — reopen any entry with its original configuration.
Scripts, tests, and mock servers
Prepare data before a request, assert on what comes back, and stand up an endpoint before the backend exists.
-
Pre-request scripts & tests
Plain JavaScript in a sandboxed QuickJS runtime, with pass/fail results and console output beside the response.
-
Local mock servers
Routes with path parameters, status codes, headers, bodies, and delays, plus a live request log — in the VS Code extension.
-
Code generation
Export any request as cURL, JavaScript (fetch), Node.js (axios), Python (requests), or Java (HttpClient).
Keyboard shortcuts
- ⌘↵Send request
- ⌘SSave request
- ⌘KSearch requests
- ⌘BToggle sidebar
- ⌘/All shortcuts
Who it's for
Real ways people use Voyager
Built for
Backend & API developers
Building and debugging endpoints across REST, GraphQL, and real-time protocols from one place.
Frontend developers
Exploring an API before wiring it up, and generating a ready-to-paste client snippet.
IoT & real-time teams
Watching MQTT topics, WebSocket frames, and event streams in a live timeline.
Teams leaving another client
Importing existing Postman or Insomnia collections without paying per seat to collaborate.
- Testing and debugging REST and GraphQL APIs
- Exploring WebSocket, SSE, MQTT, or gRPC services from one client
- Migrating an existing Postman or Insomnia collection
- Generating a ready-to-paste code snippet for a request in five languages
- Mocking an endpoint locally before the real backend exists
- Documenting an API straight from a working collection
Pricing, platforms & privacy
Good to know
-
Available
Web
12 of 14 protocols — 7 run directly in the browser; FTP, SFTP, SMTP, TCP, and UDP go through Voyager's relay when signed in.
-
Available
VS Code extension
The most complete edition: all 14 protocols, mock servers, and requests as native editor tabs.
-
Coming soon
Desktop
A lightweight Tauri app for macOS, Windows, and Linux — no public installer yet.
Pricing
Free — no paid tier, no feature gating, no seat limits, and no account required. An optional free account adds cloud sync, sharing, and teams.
Your data
Voyager is local-first: your requests, collections, and environments are stored on your device by default. Signing in is entirely optional — it adds cross-device sync, sharing, and teams, and lets the web app reach FTP, SFTP, SMTP, TCP, and UDP servers through Voyager's relay.
Guides
Learn more
REST, GraphQL, gRPC, WebSockets, or SSE? Choosing an API Protocol
A practical comparison of the major API styles — how each works, where each shines, and the trade-offs in caching, tooling, browser support, and real-time behavior — so you can choose deliberately.
Mocking an API Before the Backend Exists: A Practical Workflow
How to unblock frontend and integration work with mock APIs: agreeing on a contract first, choosing realistic responses, simulating errors and latency, and avoiding the mock-drift trap.
FAQ
Voyager questions
Is Voyager free to use?
Free — no paid tier, no feature gating, no seat limits, and no account required. An optional free account adds cloud sync, sharing, and teams.
Is my data stored or sent anywhere?
Voyager is local-first: your requests, collections, and environments are stored on your device by default. Signing in is entirely optional — it adds cross-device sync, sharing, and teams, and lets the web app reach FTP, SFTP, SMTP, TCP, and UDP servers through Voyager's relay.
What platforms is Voyager available on?
Voyager is available on: Web, VS Code extension. In development: Desktop.
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