FreeNo signupWorks with deployed MCP serversJSON-RPC validationTool discoveryAuthentication testing

Test MCP Server Online

Run authentication, health, JSON-RPC compatibility, tool discovery, resources, prompts, and protocol validation tests for any deployed MCP server.

Interactive tester

Test Your Server

Enter a deployed HTTP MCP server URL and API key to run live browser checks.

No signup

Runs from your browser against deployed HTTP MCP endpoints.
Surfaces reachability, auth, JSON-RPC, tool discovery, and latency signals.
Keeps local stdio guidance separate so the page does not overclaim browser support.

Generate Full Verification Report ->Local testing guide

Live validation

What This MCP Tester Checks

The browser tester keeps the fast endpoint checks above the fold. Broader production checks are clearly routed to MCPForge Verify so quick testing and full review stay distinct.

Live check

Authentication

Checks whether missing credentials are rejected and whether an API key works for protected JSON-RPC requests.

Live check

Health Check

Verifies the server is reachable, tries /health when available, and records response latency.

Live signal

JSON-RPC Compatibility

Sends MCP-style JSON-RPC requests and makes malformed or non-JSON responses easy to spot.

Verify signal

MCP Initialization

Use MCPForge Verify for a deeper initialize flow and capability negotiation review when you need production evidence.

Live check

Tools Discovery

Runs tools/list against the detected MCP endpoint, counts tools, and shows returned tool names.

Verify signal

Resources Discovery

Review resources/list support in the full verification path when your server exposes readable context.

Verify signal

Prompts Discovery

Review prompts/list support in the full verification path when your server ships reusable prompt templates.

Live signal

Error Handling

Flags unreachable endpoints, timeouts, CORS issues, non-JSON responses, and unexpected auth behavior.

Workflow

How to Test Your MCP Server

Use this path when your server is already deployed. If your server only runs locally over stdio, use MCP Inspector or the local MCP testing guide.

1Deploy your MCP server to a reachable HTTP endpoint.
2Enter your server URL, such as https://your-mcp-server.com/mcp.
3Add your API key when the endpoint is protected.
4Run live tests from the browser.
5Review the health, authentication, and tool discovery results.
6Generate a full MCPForge verification report when you need a deeper review.

Client independent

Supported MCP Clients

The tester validates server behavior independently of the AI client. If your server passes MCPForge tests but fails in one AI client, the issue is likely client configuration rather than server behavior.

Claude Desktop

Claude Code

Cursor

VS Code

Windsurf

Codex

OpenAI Agents where applicable

Transport accuracy

Supported MCP Transports

This page is intentionally specific about what a browser can and cannot test.

Streamable HTTP

Primary

Best fit for this online tester. Use the deployed MCP endpoint that accepts JSON-RPC over HTTP.

HTTP endpoints

Supported

Works when the endpoint exposes MCP-compatible JSON-RPC responses and permits browser requests.

STDIO

Local only

Not directly testable from a browser. Use MCP Inspector or the local MCP testing guide instead.

SSE

Legacy/limited

Some older servers use SSE. Treat browser results as limited and use Inspector for transport-level debugging.

Choose the right tool

Test MCP Server vs MCP Inspector vs MCPForge Verify

Use the online tester for quick deployed endpoint checks, MCP Inspector for local development, and MCPForge Verify for production readiness, security, governance, and public reporting.

Capability	Online MCP Tester	MCP Inspector	MCPForge Verify
Browser-based live endpoint test	Yes	Limited	Yes
Local stdio debugging	No	Yes	No
Tool discovery	Yes	Yes	Yes
Resources/prompts discovery	Verify path	Yes	Yes
JSON-RPC inspection	Fast signal	Detailed	Report signal
Security analysis	No	Manual	Yes
Governance review	No	No	Yes
Compliance signals	No	No	Yes
Public verification report	No	No	Yes
Production readiness score	No	No	Yes

Browser-based live endpoint test

Online MCP Tester: Yes
MCP Inspector: Limited
MCPForge Verify: Yes

Local stdio debugging

Online MCP Tester: No
MCP Inspector: Yes
MCPForge Verify: No

Tool discovery

Online MCP Tester: Yes
MCP Inspector: Yes
MCPForge Verify: Yes

Resources/prompts discovery

Online MCP Tester: Verify path
MCP Inspector: Yes
MCPForge Verify: Yes

JSON-RPC inspection

Online MCP Tester: Fast signal
MCP Inspector: Detailed
MCPForge Verify: Report signal

Security analysis

Online MCP Tester: No
MCP Inspector: Manual
MCPForge Verify: Yes

Governance review

Online MCP Tester: No
MCP Inspector: No
MCPForge Verify: Yes

Compliance signals

Online MCP Tester: No
MCP Inspector: No
MCPForge Verify: Yes

Public verification report

Online MCP Tester: No
MCP Inspector: No
MCPForge Verify: Yes

Production readiness score

Online MCP Tester: No
MCP Inspector: No
MCPForge Verify: Yes

Example output

Sample MCP Test Results

A clean result should make the next action obvious: keep shipping, fix auth, inspect JSON-RPC, or run a fuller verification report.

Health Checkpassed

Authenticationpassed

JSON-RPCpassed

Tools Discovery12 tools found

Resources3 resources found

Prompts2 prompts found

Error Handlingpassed

Latency184ms

Request

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list",
  "params": {}
}

Response snippet

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "tools": [
      { "name": "search_docs" },
      { "name": "create_ticket" },
      { "name": "summarize_issue" }
    ]
  }
}

Validation model

How MCPForge Tests Servers

MCPForge separates quick browser checks from deeper verification so each result is useful without pretending to be a complete audit.

Reachability

Authentication behavior

JSON-RPC compatibility

MCP method checks

Tool, resource, and prompt discovery

Response structure validation

Latency and health signals

Production readiness recommendations

Troubleshooting

Common MCP Server Test Failures

Most failures are configuration, transport, or response-shape issues. These cards keep the fix close to the error.

Server URL is wrong

What it means: The tester cannot reach the endpoint you entered.

How to fix it: Check the protocol, hostname, path, and whether your MCP route is /mcp, /api/mcp, or root.

Related guide ->

API key missing or invalid

What it means: The server rejected the request or returned an auth-related error.

How to fix it: Paste the same key your deployed server expects and confirm the auth header format.

Related guide ->

/health endpoint missing

What it means: The health endpoint is not available, but the MCP endpoint may still work.

How to fix it: Add a lightweight health route for operations, or rely on JSON-RPC checks for compatibility.

Related guide ->

tools/list not implemented

What it means: The server did not return a tools array from the MCP tool discovery method.

How to fix it: Implement tools/list and return valid tool metadata with names and input schemas.

Related guide ->

CORS or reverse proxy issue

What it means: The browser cannot complete the request even though the server may be running.

How to fix it: Review allowed origins, proxy headers, and whether the deployed endpoint supports browser requests.

Related guide ->

JSON-RPC response malformed

What it means: The server responded, but the response did not look like a valid JSON-RPC result or error.

How to fix it: Return jsonrpc, id, and either result or error using the expected JSON-RPC 2.0 shape.

Related guide ->

Server only supports stdio

What it means: The server works locally in an MCP client but has no browser-reachable HTTP endpoint.

How to fix it: Use MCP Inspector locally, or deploy an HTTP transport before using the online tester.

Related guide ->

Server times out

What it means: The endpoint did not respond before the browser-side timeout.

How to fix it: Check cold starts, upstream APIs, long-running tool calls, and hosting timeouts.

Related guide ->

OAuth flow not completed

What it means: The endpoint expects an interactive authorization flow the quick tester cannot complete.

How to fix it: Complete OAuth in the target client or use a bearer token flow before testing.

Related guide ->

Method not found

What it means: The server rejected tools/list, resources/list, prompts/list, or another MCP method.

How to fix it: Confirm the server implements the method and that the request is hitting the MCP endpoint, not a web page.

Related guide ->

FAQ

MCP Server Tester FAQ

Short answers for the most common questions about online testing, local stdio servers, client behavior, and verification.

What is an MCP server tester?+

An MCP server tester is a developer tool that sends live requests to an MCP endpoint and reports whether the server is reachable, authenticated correctly, and compatible with core MCP JSON-RPC behavior.

How do I test an MCP server online?+

Deploy the server to an HTTP endpoint, enter the URL, add an API key if required, and run the browser-based tests. Use MCPForge Verify when you need a deeper production readiness report.

Can I test a local MCP server?+

Not directly from this browser tester unless the local server is exposed through a reachable HTTP endpoint. For local development, use MCP Inspector or the local MCP testing guide.

Can I test a stdio MCP server in the browser?+

No. Stdio MCP servers run through standard input and output, so they need a local client or MCP Inspector rather than a browser endpoint test.

Does this work with Claude Desktop?+

Yes, it can help validate the server independently of Claude Desktop. If the server passes here but fails in Claude Desktop, check the Claude configuration and local transport setup.

Does this work with Cursor?+

Yes. The tester checks the server endpoint independently of Cursor, which makes it useful for separating server issues from client configuration issues.

What does tools/list test?+

tools/list asks the server for the tools it exposes to MCP clients. A good response includes tool names, descriptions, and schemas clients can use safely.

Does the tester validate resources and prompts?+

The quick browser tester focuses on deployed endpoint reachability, authentication, JSON-RPC response shape, and tool discovery. Use MCPForge Verify for broader resources and prompts validation.

Does the tester store my API key?+

The browser tester uses the API key only in your current browser session to send the requested test to the endpoint you enter. It does not send the key to an MCPForge API route.

What is the difference between Test MCP Server and Verify MCP?+

Test MCP Server is a fast live check for deployed endpoints. Verify MCP adds a fuller production readiness review with security, governance, compliance, and report signals.

What should I do if my MCP server times out?+

Check whether the server is awake, reachable from the public internet, responding within hosting limits, and not blocked by a slow upstream dependency.

Is this MCP tester free?+

Yes. The online MCP tester is free to use and does not require signup.

Keep going

Related Guides

Use these guides when you need command-line testing, local debugging, production hardening, or reusable MCP server templates.

Test MCP Server with curl Test MCP Server with Postman Test a Local MCP Server MCP Inspector: Complete Guide How to Fix MCP Error -32001 How to Fix MCP Error 32603 Running MCP in Production How to Secure an MCP Server Code Hub templates

Ready for a deeper MCP server review?

The online tester is ideal for quick validation. If you need a full production readiness review, run MCPForge Verify.

Generate Full Verification Report ->Browse Production MCP Templates ->