Test your MCP server in every major AI client.
From your first prompt to a continuous gate on every release, MCPJam shows what breaks across every AI client, and how to fix it.
Test in 16+ major AI clients
Get your agent set up with MCPJam
Launch locally or in web
ChatGPTs-2291-c3Show page views and signups for the last 7 days.
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PULSE · MCP APPDemo dataPage views
24,800
Sep 8–14 · Last 7 days
Claudes-2291-a1Show page views and signups for the last 7 days.
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PULSE · MCP APPDemo dataSignups
386
Sep 8–14 · Last 7 days
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Inspector
See the same prompt land in multiple clients.
Call a tool, read the trace, and compare how your product appears in different clients.
ChatGPTs-2291-c3Claudes-2291-a1Ask something… Use Slash “/” commands for Skills & MCP prompts
Swarms
Test the journeys your users actually take.
Agent personas run them across every client. Every session is captured and scored.
Create a swarm of your users
Simulated users run through your server so you can see what breaks.
Choose the clients and servers your users will interact with. *
This will shape the swarm's behavior. You will be able to compare behavior across clients side by side.
ChatGPT
Claude
Cursor+ Add clientDescribe your users and their behavior. *
We build the user goals from your input. Your inputs are not final. You can edit personas and goals on the next screen.
Generated personas
- MCMaya Chen · Support agentFind the duplicate charge on order A-2291 and refund it.8 × 3 clients
- JHJordan Hale · Finance opsMatch payout po_7Hd2 to its charges and flag anything missing.8 × 3 clients
- PSPriya Shah · DeveloperCreate an invoice, fail its payment, and confirm the webhook fires.8 × 3 clients
User Testing
Then invite real people to try the same ones.
Share a sandboxed chatbox. Measure user sentiment and uncover usability gaps.
Access settings
Has access
- MMara Okafor (you)[email protected]Owner
Dana Reyes[email protected]Tester- Luis Moreno[email protected]Tester
- Sam Kaur[email protected]Tester
Ratings
Per-turn ratings
Preview
ChatGPTCopy linkRefund the duplicate charge on order A-2291
I found two charges for order A-2291: ch_3RkA9 for $129.00 and ch_3RkQ9 for $129.00, 41 seconds apart. I refunded ch_3RkQ9 as a duplicate. The customer will see it in 5 to 10 business days.
AI can make mistakes. Please double-check responses.
Previewing as you, signed in. A tester opening this link gets the guest experience, which can differ.
Evaluate
Set the quality bar for every client.
Lock in the behaviors you want always working. The next run tells you if they held, and in which client.
Evaluate
Suite health
98%average across 12 runs
Runs
| Run | Suite | Client | Result | Rate | Platform | Date | Latency | Tokens | Calls |
|---|---|---|---|---|---|---|---|---|---|
| #128 | Payments operations | | Failed | 96%69/72 | GitHub | Sep 13, 2:00 AM | 18.4s | 16.2k | 44 |
| #127 | Payments operations | | Passed | 98%71/72 | CLI | Sep 12, 2:00 AM | 14.2s | 12.1k | 41 |
| #126 | Treasury reconciliation | | Passed | 100%48/48 | SDK | Sep 12, 1:14 AM | 16.8s | 15.6k | 38 |
| #125 | Billing exception handling | | Failed | 94%45/48 | CLI | Sep 11, 11:42 PM | 21.1s | 18.9k | 47 |
| #124 | Payments operations | | Passed | 99%71/72 | GitHub | Sep 11, 2:00 AM | 11.3s | 9.4k | 29 |
| #123 | Dispute resolution | | Passed | 100%36/36 | SDK | Sep 10, 6:18 PM | 15.5s | 11.8k | 33 |
| #122 | Treasury reconciliation | | Passed | 97%70/72 | GitHub | Sep 10, 2:00 AM | 17.9s | 14.7k | 40 |
CI/CD
Block the ones that fail before they merge.
Run the same suite on every pull request. A failing check blocks the merge.
list_charges: return full charge objects #482
release/2.15Some checks were not successful
1 failing and 4 successful checks
- BuildSuccessfulRequired
- Unit testsSuccessfulRequired
- MCPJam / Protocol conformanceSuccessfulRequired
- MCPJam / OAuth & securitySuccessfulRequired
- MCPJam / Evals89% pass rate · 95% requiredRequired
Merging is blocked
MCPJam Evals must pass before this pull request can be merged.
Questions
Before you start jamming.
No. MCPJam maintains each client's current behavior so your tests reflect what users experience today.
With evaluation, not brittle assertions. MCPJam scores tool choice, arguments, and goal completion across repeated runs, then shows why the score changed.
Those products evaluate an agent you control. MCPJam tests how external AI clients use your MCP server.
MCPJam is pre-production and never sees live traffic. The Inspector runs locally or in your CI; enterprise controls include SSO, audit logs, and a DPA.
Yes. The Inspector, CLI, SDK, local evals, and conformance checks are open source and free.
Ship knowing it works, for every user, in every client.