MCPJam inspector is the local testing tool for ChatGPT apps and MCP servers. Build your apps locally with MCPJam's widget emulator and test against any LLM in the playground. Inspect your MCP server’s tools, resources, prompts, and OAuth flows. No more ngrok or ChatGPT subscription needed.
We started MCPJam because the dev experience around building ChatGPT apps, MCP apps, and MCP servers wasn't great.
To develop a ChatGPT app, you had to get a ChatGPT pro subscription, ngrok you local MCP server, then connect it remotely on ChatGPT. There were also no good ways to test MCP servers and see how they behave in a real production environment.
That inspired us to build our open source inspector at MCPJam. We introduced:
Local ChatGPT and MCP apps emulator.
LLM playground to test your MCP server / apps in a real chat environment with any LLM
OAuth debugger to visualize MCP authorization at every step
and a bunch of other features that addresses the pains of MCP development.
If you're building a ChatGPT app, MCP app, or MCP server, I highly invite you to give us a try! Feel free to email me if you have any questions or feedback.
Interesting! We are actually building a travel AI service based on ChatGPT, we’ll review it with the team.
Great product. We use it heavily at Ghost Team and have used it for many of the ChatGPT apps that we're building for our clients. Would highly recommend it's the quickest and easiest way to do your testing.
i’m glassBead, creator of Thoughtbox, an MCP server that enables self-observability for Claude Code agents, and helps CC calibrate a project to become more usable over time.
i’ve been using MCPJam from very nearly Day One to test Thoughtbox features that few coding agents support yet, and it’s an indispensable part of our stack. the creators are among the top MCP developers in the game. month after month, they’ve consistently anticipated the needs of devs on the frontier of agent-user tech: no small order.
if you’re in the business of making things agents want, using MCPJam is non-negotiable.
glassBead
MCP Jam is my goto testing tool when I build ChatGPT apps. The UI is neat and it provides all tools necessary to debug yours!
Great work team! Good to see MCP jam on producthunt. Its focus on local development helped us for testing our MCP servers.
The OAuth debugger looks really useful for troubleshooting authentication flows. I'm curious about testing MCP servers that connect to multiple external services — does the inspector support visualizing parallel OAuth flows or handling multiple tokens at once?
@matteo8p The ngrok + ChatGPT subscription tax for local dev is such an underrated pain point. Every extra hoop kills momentum. We’re building consumer-facing AI (group chat participant) and the iteration bottleneck hits us too. Do you see MCPJam eventually supporting testing with custom personas/personalities, or is it purely for tool/server validation?
Our team at Tadata builds MCP servers every day. We maintain one of the leading open source MCP projects and are shipping a large number of MCP servers for our agent builder. And we're huge fans of the OG MCPJam tool for debugging OAuth issues -- the visual flow is so helpful! Excited to try out the new stuff.
MCPJam is an amazing product with polished UX that has become our daily driver for troubleshooting. I only wish we had the OAuth inspector sooner, it would have saved us days of frustration! We now trust it as the de facto standard for validating new features. This is a must-have tool that feels like the start of an 'Android Studio' for ChatGPT apps. Good luck
Nice focus on the local development workflow - the "no more ngrok or ChatGPT subscription needed" angle is a real pain point.
The tool inspector for resources, prompts, and OAuth flows looks especially useful. Debugging OAuth in MCP integrations has been frustrating in my experience.
One question: does the LLM playground support streaming responses, or is it request/response only? We've found streaming adds complexity when testing tool interactions.
Great launch - the MCP tooling ecosystem needs more developer-focused products like this.
Congratulations on the launch! MCPJam was clutch when we were building and testing MCP apps at Noodle Seed.
Hey, it's Matt from MCPJam 👋.
We started MCPJam because the dev experience around building ChatGPT apps, MCP apps, and MCP servers wasn't great.
To develop a ChatGPT app, you had to get a ChatGPT pro subscription, ngrok you local MCP server, then connect it remotely on ChatGPT. There were also no good ways to test MCP servers and see how they behave in a real production environment.
That inspired us to build our open source inspector at MCPJam. We introduced:
Local ChatGPT and MCP apps emulator.
LLM playground to test your MCP server / apps in a real chat environment with any LLM
OAuth debugger to visualize MCP authorization at every step
and a bunch of other features that addresses the pains of MCP development.
If you're building a ChatGPT app, MCP app, or MCP server, I highly invite you to give us a try! Feel free to email me if you have any questions or feedback.
GitHub: https://github.com/MCPJam/inspector
Email: [email protected]