Deploy and Host MCPJam Inspector with Railway

MCPJam Inspector is the open-source testing and evaluation platform for MCP server developers. This template compiles it from the official source tree and runs it as one Railway service — a Hono/Node API plus a compiled React client — behind a public HTTPS URL. You get tools, resources, prompts, the OAuth debugger, a widget emulator and the LLM playground, with no node, no docker and no tunnel on your machine. Access is gated by the Inspector's own session token, which Railway generates for you.

About Hosting MCPJam Inspector

The Inspector normally runs locally (npx @mcpjam/inspector, or a desktop app). Hosting it buys you a URL: test an MCP server from a phone or a second machine, hand a colleague a live server configuration instead of a stale JSON snippet, and keep a standing rig pointed at staging. The app is stateless, so there is no database, no volume and no migration — one service, one public URL.

Works hosted: any public HTTPS MCP server (Streamable HTTP and SSE), including OAuth-protected ones; tools, resources, prompts, elicitation, logging, conformance checks; the LLM playground with your own key; the ChatGPT-apps / MCP-apps widget emulator; the OAuth debugger.

Does not work hosted: STDIO servers (a container has no npx of yours), localhost servers, reading your machine's ~/.mcp or skills, and tab-to-tab continuations designed for 127.0.0.1. The terminal and browser tools are disabled by this template — see Security.

Getting in: the Inspector is gated by a URL fragment, not a login. After the deployment succeeds, open the service's deploy log and copy the printed link:

✔ MCPJam Inspector is ready
  ➜ Open MCPJam
  https://YOUR-SERVICE.up.railway.app/#token=YOUR-TOKEN

Open that whole link in a browser; the #token= fragment signs the browser in and is stripped from the address bar.

Common Use Cases

Reproduce an MCP client's failing call end to end, with a URL a teammate can open instead of a log file.
Debug OAuth message by message — /authorize → /token across protocol versions, including DCR and CIMD.
Render a ChatGPT-apps or MCP-apps widget in the built-in emulator, without ChatGPT, ngrok or a local dev server.
Share one live MCP server configuration with a teammate, an agency client or a QA reviewer, and keep a public demo of your server for prospects.

Dependencies for MCPJam Inspector Hosting

Nothing. This template is a single service with no database, no volume, no sidecar and no third-party account to sign up for. The build itself pulls Node 24, Chromium and Playwright from their public upstreams inside Railway's builder.

Deployment Dependencies

MCPJam Inspector (upstream source) — vendored here at a pinned commit.
MCPJam documentation · mcpjam.com
Build-time network egress to registry.npmjs.org, cdn.playwright.dev and the Debian apt mirrors. A build failure there is an egress problem, not a code problem — redeploy.

Implementation Details

Variable	Value	Why
`MCPJAM_SESSION_TOKEN`	generated, 32 chars	The credential in the access link
`MCPJAM_ALLOWED_HOSTS`	`${{RAILWAY_PUBLIC_DOMAIN}}`	Host allowlist for the token gate and the browser Origin check
`ALLOWED_ORIGINS`	`https://${{RAILWAY_PUBLIC_DOMAIN}}`	Exact origins allowed to call the API
`MCPJAM_INSPECTOR_FRONTEND_URL`	`https://${{RAILWAY_PUBLIC_DOMAIN}}`	The address the app prints and builds callbacks from
`PORT`	`6274`	Keeps the app and Railway's health check on one port
`MCPJAM_LOCAL_COMPUTER_ENABLED`	`false`	No shell on a public URL
`MCPJAM_LOCAL_BROWSER_ENABLED`	`false`	Same
`RAILWAY_HEALTHCHECK_TIMEOUT_SEC`	`600`	Room for the first, slower start

Because these reference RAILWAY_PUBLIC_DOMAIN, they follow your domain automatically. If you attach a custom domain, update the two allowlist variables by hand. Health check is GET /health — public and unauthenticated by design, which is what lets Railway probe it.

On the deploy screen, accept the template's values. Railway asks you to confirm the four whose values are literal: PORT, MCPJAM_LOCAL_COMPUTER_ENABLED, MCPJAM_LOCAL_BROWSER_ENABLED and RAILWAY_HEALTHCHECK_TIMEOUT_SEC. Do not blank the two false flags: the app reads them as MCPJAM_LOCAL_COMPUTER_ENABLED !== "false", so an empty value does not mean "off" — it enables the terminal tool. That is the one way to end up with a public shell on a public URL.

Why Deploy MCPJam Inspector on Railway?

One click to a working URL — no local toolchain, no tunnel, no firewall rule, no second machine.
A reproducible build — the source is pinned and built with upstream's own Dockerfile, so a deployment is a known-good artifact.
HTTPS by default — Railway terminates TLS. That matters here: browsers will not grant a widget iframe the permissions it needs over plain HTTP.
No lock-in — the same Inspector runs from npx, a desktop app or a container. Railway hosts it; it does not own it.
Cheap and disposable — one stateless service, no state to migrate, and sleeping or deleting it is a complete off switch.

Cost: ~US$5–6 per month always-on — measured at 0.46 GB resident memory and 0.02 % of one vCPU while idle, billed at Railway's usage rates of US$10 per GB-month of memory and US$20 per vCPU-month. Limits are ceilings, not reservations, so a generous cap costs nothing until it is used. Turn on App Sleeping to cut the idle cost; the token is pinned in a variable, so the access link survives a sleep (in-memory state does not).

Security

URL + token is the entire security model. No accounts, no login, no rate limit. Treat the access link like an SSH deploy key, and rotate the token when someone leaves.
Terminal and browser tools are off by default. Re-enabling MCPJAM_LOCAL_COMPUTER_ENABLED hands an arbitrary shell to anyone with the link. Inside a container it is not your laptop's shell, but it is still a shell.
*.up.railway.app hostnames are guessable from your project name; a custom domain you control can be pointed elsewhere or taken down.
The origin allowlist is not a firewall — it stops cross-origin browsers and DNS rebinding. The token is what authorises access.
Anyone signed in can spend your LLM credits and make the Inspector call tools on any server they connect. This is a development tool, not a production front end.

Troubleshooting

Every request returns 403 {"error":"Forbidden"}. The origin check. Set MCPJAM_ALLOWED_HOSTS to your exact hostname (no scheme, no path) and ALLOWED_ORIGINS to https://your-hostname, then redeploy. This is the usual cause after adding a custom domain.

"Session token required" / "Invalid session token". The link lost its fragment. Copy the whole link from the deploy log, including #token=…, or set your own MCPJAM_SESSION_TOKEN and redeploy.

A plain URL shows instructions instead of the app. By design — open it through the access link so it can sign the browser in.

Widget rendering says the browser is unavailable. Chromium is baked into the image, but a sandbox can deny it some syscalls. Core inspection, logging, OAuth and the playground are unaffected.

The health check fails on the first deploy. Raise RAILWAY_HEALTHCHECK_TIMEOUT_SEC further (the template sets 600) and redeploy; the first container start initialises the Inspector's services before it serves.

About this template

This is a community deployment packaging, not the upstream product. It vendors the MCPJam Inspector source at a pinned commit and changes no application code, no Dockerfile and no dependency.

Full deployment guide: github.com/BURNI80/mcpjam-inspector-railway