Test + develop ChatGPT apps and MCP apps (ext-apps) locally
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.
“Test + develop ChatGPT apps and MCP apps (ext-apps) locally”
MCPJam Inspector launched on Product Hunt on January 20th, 2026 and earned 147 upvotes and 39 comments, placing #10 on the daily leaderboard. 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.
On the analytics side, MCPJam Inspector competes within Open Source, Developer Tools and GitHub — topics that collectively have 620.6k followers on Product Hunt. The dashboard above tracks how MCPJam Inspector performed against the three products that launched closest to it on the same day.
Who hunted MCPJam Inspector?
MCPJam Inspector was hunted by Matthew Wang . A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
Matthew Wang 
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]