Question 1

What is an online API client and how does it work?

Accepted Answer

An online API client is a web-based developer tool that allows you to construct, send, and debug HTTP requests (such as GET, POST, PUT, PATCH, and DELETE) directly in your browser without desktop installations. It provides an intuitive GUI for editing headers, parameters, auth tokens, and request bodies, rendering server responses in real time.

Question 2

How is EpochMasters API Client different from Postman or Insomnia?

Accepted Answer

EpochMasters API Client is 100% free, requires zero installation, and requires no account creation or login. Unlike modern versions of Postman that mandate cloud logins, our tool stores your collections, requests, and history entirely in your local browser storage (localStorage). Furthermore, our built-in backend CORS proxy allows you to send requests to any remote API without running into "Cross-Origin Request Blocked" browser security errors.

Question 3

How does the built-in Cloudflare CORS Proxy work?

Accepted Answer

Modern web browsers enforce the Same-Origin Policy (SOP) and block client-side JavaScript from fetching data from external domains that lack permissive Access-Control-Allow-Origin headers. When enabled, our API client routes the HTTP request through Cloudflare's high-speed global Edge Worker proxy (with automatic failover to our local backend proxy). Cloudflare executes the request at the edge where browser CORS restrictions do not apply, delivering the real status code, latency, and response headers back to your browser seamlessly.

Question 4

How do I import a cURL command into the API client?

Accepted Answer

Click the "cURL" button in the top toolbar, paste your bash or command-line curl snippet into the text area, and click "Import cURL". The tool automatically parses the HTTP method, destination URL, headers (-H), authorization tokens, and payload body (--data or -d) into the workbench.

Question 5

Are my API keys, bearer tokens, and confidential payloads secure?

Accepted Answer

Yes. Your request configurations, collections, environment variables, and authentication secrets are stored exclusively in your browser's local storage. They are never logged, stored in databases, or shared with third parties.

Question 6

Can I test APIs running on localhost or private local networks?

Accepted Answer

Yes! To test localhost services (e.g., http://localhost:3000, http://127.0.0.1:8000), disable the "CORS Proxy" toggle in the Settings tab so the request is dispatched directly from your browser to your local development server.

Question 7

How do Environment Variables like {{baseUrl}} work?

Accepted Answer

Environment variables allow you to define reusable key-value pairs (such as baseUrl, apiKey, or userToken) across different environments like Development, Staging, and Production. You can insert variables into your URLs, headers, parameters, and JSON bodies using double curly braces (e.g., {{baseUrl}}/api/v1/users). When you click Send, the client dynamically substitutes each variable with its active value.

Question 8

Does the tool automatically detect Unix Epoch timestamps in JSON responses?

Accepted Answer

Yes! As part of the EpochMasters developer suite, our response viewer automatically identifies numeric Unix timestamps (in seconds, milliseconds, or microseconds) inside JSON response keys and values, displaying human-readable dates upon hover or inline inspection.

Method	Description & Intent	Has Body?	Idempotent?	Typical Status Codes
GET	Retrieves representation of a resource without side effects.	No	Yes	200 OK, 304 Not Modified, 404
POST	Submits an entity to the specified resource, often resulting in state change or record creation.	Yes (JSON/Form)	No	201 Created, 200 OK, 400 Bad Request
PUT	Completely replaces all current representations of the target resource with the payload.	Yes	Yes	200 OK, 204 No Content
PATCH	Applies partial modifications to a resource (only changed fields).	Yes	No	200 OK, 204 No Content
DELETE	Deletes the specified resource by ID or query criteria.	Optional	Yes	200 OK, 204 No Content, 404
HEAD	Identical to GET, but returns only response headers without response body.	No	Yes	200 OK, 404 Not Found
OPTIONS	Describes communication options, supported methods, and CORS headers for target resource.	No	Yes	200 OK, 204 No Content

Feature	EpochMasters	Postman Desktop	Insomnia	cURL CLI
Installation Required	None (In Browser)	500MB+ Desktop App	Desktop App	CLI Installed
Account / Sign-in Wall	Never Required	Mandatory Cloud Account	Account Required	None
CORS Bypass Proxy	Built-in 1-Click	Desktop bypass only	Desktop only	N/A (CLI)
Bidirectional cURL Tool	Import & Export	Import & Code gen	Import & Code gen	Native syntax
Epoch Timestamp Decoding	Integrated Automatically	Requires custom script	No	No
Local Privacy & Security	100% Stored in Browser	Synced to cloud	Synced to cloud	Local machine
Cost	100% Free Forever	Freemium / Paid Tier	Freemium / Paid Tier	Free Open Source

No Response Loaded

Free Online REST API Client & HTTP Request Tester

Why Developers Choose EpochMasters Online API Client

All HTTP Methods Supported

CORS Bypass Proxy

Bidirectional cURL Generator

Flexible Authentication Handlers

Environments & Dynamic Variables

Smart JSON & Epoch Time Viewer

How to Test a REST API Online in 4 Simple Steps

Select Method & URL

Set Headers & Params

Configure Body & Auth

Send & Inspect Response

Supported HTTP Methods & Best Practice Specifications

EpochMasters API Client vs Traditional API Clients

Frequently Asked Questions (FAQ)

Explore More Free Developer Tools

JSON Parser & Formatter

WebSocket Client Tester

Unix Epoch Converter

Code Generator