MCP Inspector review

Q: How do I install MCP Inspector?

Run npx @modelcontextprotocol/inspector. It needs Node.js >=22.19.0. The install section above has the other options from the project's README.

MCP Inspector is a developer tool for testing and debugging Model Context Protocol servers through a web UI, CLI, or terminal UI.

Updated Nov 1, 2026. Review written Oct 22, 2026 from the project's own sources; usage data refreshed every Monday.

TL;DR

MCP Inspector is the reference developer tool for testing and debugging MCP servers. It is for developers building or checking MCP servers. One package provides a browser inspector, a scriptable CLI for CI and coding agents, and a terminal UI, all built on one shared core.

11.2kGitHub stars
+61new stars, week of Oct 25
~740.7kdownloads a week, +42% vs 4-week avg
#13in MCP and agent tools this week

MCP Inspector at a glance

Category: MCP and agent tools
Maintained by: Model Context Protocol (organization, @modelcontextprotocol on GitHub)
Language: TypeScript, JavaScript, CSS
Repository: github.com/modelcontextprotocol/inspector
Website: modelcontextprotocol.io/docs/2026-07-28/tools/inspector
npm package: @modelcontextprotocol/inspector 2.12.0
Latest release: 2.12.0 on GitHub, Oct 21, 2026
First published: Oct 3, 2024

What MCP Inspector does

MCP Inspector provides a web client, a Vite + React + Mantine single-page app with a Node backend, for graphical server inspection.
MCP Inspector includes a scriptable CLI for automation, CI, shell pipelines, and coding agents, with JSON output.
MCP Inspector offers an interactive terminal UI built with Ink, for when a browser isn't available or wanted.
MCP Inspector ships mcpdo, an experimental client that connects once and runs many commands through an implicit local daemon.
MCP Inspector can list a server's tools and call tools with arguments from the command line.
MCP Inspector handles OAuth tokens, OAuth client secrets, and stdio env values, storing them in the OS keychain by default.
MCP Inspector supports legacy and modern 2026-07-28 protocol-era negotiation across all clients.

How to install and start using MCP Inspector

Web UI with npx

npx @modelcontextprotocol/inspector

CLI with npx

npx @modelcontextprotocol/inspector --cli

TUI with npx

npx @modelcontextprotocol/inspector --tui

Requirements

Node.js 22.19.0 or newer.
An OS keychain for encrypted secret storage; otherwise secrets go to ~/.mcp-inspector/secrets.json.

First steps

Launch the web UI against a local stdio server with npx @modelcontextprotocol/inspector node path/to/server/index.js.
Open the printed URL, which carries a per-launch API token. Set MCP_AUTO_OPEN_ENABLED=false to stop the browser opening automatically.
List a server's tools from the CLI with npx @modelcontextprotocol/inspector --cli node path/to/server/index.js --method tools/list.

Who MCP Inspector is for

Developers building MCP servers who want to test and debug them interactively in a browser.
Teams smoke-testing MCP servers in CI or shell scripts using JSON output and exit codes.
Coding agents that need fast, machine-readable feedback from MCP servers.
Developers working in terminals or SSH sessions without a browser, using the TUI.

Limitations to know

MCP Inspector saves secrets unencrypted in ~/.mcp-inspector/secrets.json on machines without a keychain, unless you supply a key.
MCP Inspector's mcpdo client is experimental.
MCP Inspector v1 is deprecated and receives security fixes only; moving to v2 changes CLI flags and the Node requirement.
MCP Inspector releases 2.0.0 through 2.11.0 have three vulnerabilities fixed in 2.12.0.

Is MCP Inspector growing? Usage data

In the week of Oct 25–31, 2026, MCP Inspector ranked #123 on the Devtoolwatch Board and #13 in MCP and agent tools, with a momentum score of 58 out of 100. Its main package had about 740.7k downloads that week, +42% against its own 4-week average.

New GitHub stars per week for the last 12 weeks, from GitHub's stargazer history (today's stargazers by the week they starred).

Show the weekly numbers

New GitHub stars per week for MCP Inspector
Week of	New stars
Aug 9, 2026	52
Aug 16, 2026	59
Aug 23, 2026	69
Aug 30, 2026	49
Sep 6, 2026	47
Sep 13, 2026	43
Sep 20, 2026	54
Sep 27, 2026	50
Oct 4, 2026	55
Oct 11, 2026	46
Oct 18, 2026	56
Oct 25, 2026	61

On Hacker News

Zero-Touch OAuth for MCP, 278 points and 103 comments (Jun 18, 2026)
New MCP Roadmap, 270 points and 161 comments (Aug 22, 2026)
MCP Specification – version 2025-06-18 changes, 200 points and 121 comments (Jun 18, 2025)
MCP Apps: Extending servers with interactive user interfaces, 192 points and 121 comments (Nov 23, 2025)
MCP 2026-07-28 Specification: transport going stateless, 127 points and 41 comments (Jul 28, 2026)

The Board ranks tools by four signals each week: new stars, new stars for the repo's size, added downloads and download growth beyond the market. How the ranking works.

MCP Inspector alternatives

Other MCP servers and agent tools on the Board in the week of Oct 25–31, 2026, by momentum:

MCP and agent tools ranked by momentum, the week of Oct 25–31, 2026
Rank	Tool	Stars	Downloads/wk
#1	REAREA is an MCP server and CLI that lets coding agents reverse engineer native binaries, JavaScript and Electron apps, .NET assemblies,…	415.5k	760.6k
#2	ha-mcpha-mcp is an unofficial Model Context Protocol server that lets AI assistants control and manage Home Assistant using natural language.	5.4k	118.1k
#3	TregTreg is a registry and proxy that gives AI agents one token for a catalog of paid third-party API endpoints and team-shared tools.	6.9k	6.7k
#4	Chrome DevTools MCPChrome DevTools MCP is an MCP server and CLI that lets coding agents control and inspect a live Chrome browser using Chrome DevTools.	54.6k	2.7M
#5	codebase-memory-mcpHigh-performance code intelligence MCP server. Indexes codebases into a persistent knowledge graph — average repo in milliseconds. 162…	47.9k	–
#6	open-computer-use👾 Open Computer Use – Open-Source Alternative to Codex Computer Use	2.8k	–

All MCP servers and agent tools, ranked

Recent MCP Inspector releases

2.12.0, Oct 21, 2026
1.0.3, Oct 21, 2026
2.11.0, Oct 14, 2026
2.10.1, Oct 8, 2026
2.10.0, Oct 7, 2026

MCP Inspector FAQ

Is MCP Inspector free and open source?

MCP Inspector's code is on GitHub (modelcontextprotocol/inspector), but the repository doesn't declare a standard open-source license. Check its license file before using it commercially.

How do I install MCP Inspector?

Run npx @modelcontextprotocol/inspector. It needs Node.js >=22.19.0. The install section above has the other options from the project's README.

Is MCP Inspector still maintained?

Yes. The modelcontextprotocol/inspector repository was last updated on Oct 21, 2026, and the latest release, 2.12.0 on GitHub, came out on Oct 21, 2026.

How popular is MCP Inspector?

MCP Inspector has 11.2k GitHub stars as of Nov 1, 2026. It gained 61 new stars in the week of Oct 25–31, 2026, against a 12-week average of 53 a week. Its main package had about 740.7k downloads that week, +42% against its own 4-week average. That made it #13 among MCP servers and agent tools on the Devtoolwatch Board.

What are the best alternatives to MCP Inspector?

Other MCP servers and agent tools on the Devtoolwatch Board in the week of Oct 25–31, 2026, by momentum: REA (#1), ha-mcp (#2), Treg (#3), Chrome DevTools MCP (#4), codebase-memory-mcp (#5). The alternatives table above has their numbers.

What is MCP Inspector used for?

MCP Inspector is used for testing and debugging MCP servers. You can connect to a local or remote server, list its tools, call tools, and watch the JSON-RPC exchange in a browser, on the command line, or in a terminal UI.

Is MCP Inspector an MCP client?

Yes. MCP Inspector provides several clients: a web client, a CLI client, a TUI client, and the experimental mcpdo connection client. They all connect to MCP servers through one shared core.

How does MCP Inspector work?

MCP Inspector runs through npx. You pass the server's launch command or a remote URL. A single binary dispatches to the web, CLI, or TUI client. All three share transports, configuration files, and OAuth state on disk, so a connection behaves the same in each.

Where does MCP Inspector store secrets?

MCP Inspector stores OAuth tokens, client secrets, and stdio env values in the OS keychain by default. Without a keychain, such as on headless Linux, SSH sessions, or containers, it saves them to ~/.mcp-inspector/secrets.json, unencrypted unless you supply a key.

Sources

MCP Inspector README badge

Maintainers can show the tool's weekly Board rank in their README:

[![Devtoolwatch](https://index.devtoolwatch.com/badge/mcp-inspector.svg)](https://index.devtoolwatch.com/tools/mcp-inspector/)

How this page is made: Devtoolwatch writes each review from the project's README, releases, package metadata and website, with an AI model, then checks every claim against the source it cites and drops what the sources don't support. The numbers come from Devtoolwatch's daily GitHub snapshots, GitHub's stargazer history, and the npm and PyPI download APIs. Spotted an error? Email [email protected].