by
Connects to any MCP server using HTTP streamable or Server‑Sent Events and presents the interaction in a chat‑like UI, enabling quick testing and debugging of MCP endpoints.
The tool provides a lightweight, standalone Actor that acts as a bridge between a browser UI and an MCP server. It establishes a streamable HTTP or SSE connection, forwards user queries, receives real‑time responses (including tool calls), and renders the whole conversation in a chat interface.
npm install
, set APIFY_TOKEN
and optional LLM_PROVIDER_API_KEY
in a .env
file, then start with npm start
. Open http://localhost:3000
in a browser.https://…runs.apify.net
and open it. The UI will let you type queries and see streamed responses.Do I need an LLM provider API key? No. The client can run using Apify’s built‑in LLM integration. Provide your own key only if you prefer a specific provider.
Is the project open source? Yes, the source code is hosted on GitHub (https://github.com/apify/tester-mcp-client).
What is the pricing model? Pay‑per‑event: you are charged for actor start, runtime, and each answered query (free when using your own LLM key). The free tier allows ~80 hours of run time per month.
Can I run the client locally?
Absolutely. Clone the repo, install dependencies with npm, configure .env
, and start with npm start
.
Which transport methods are supported? Both HTTP streamable (preferred) and Server‑Sent Events (SSE) are supported.
What limitations exist? The client does not implement all MCP features such as Prompts and Resource handling.
Tester MCP Client
Pricing
Pay per event
Developed by
Maintained by Apify
A model context protocol (MCP) client that connects to any MCP server using Server-Sent Events (SSE) and displays the conversation in a chat-like UI. It is a standalone Actor server designed for testing MCP servers over SSE.
5.0 (5)
Pricing
Pay per event
20
704
107
Last modified
6 days ago
READMEInputPricingAPISource codeIssues
https://apify.com/jiri.spilka/tester-mcp-client
Implementation of a model context protocol (MCP) client that connects to an MCP server using HTTP streamable (recommended) or Server-Sent Events (SSE) transport and displays the conversation in a chat-like UI. It is a standalone Actor server designed for testing MCP servers over HTTP streamable or SSE. It uses Pay-per-event pricing model.
For more information, see the Model Context Protocol website or blogpost What is MCP and why does it matter?.
Once you run the Actor, check the output or logs for a link to the chat UI interface to interact with the MCP server. The URL will look like this and will vary each run:
Navigate to https://...apify.net to interact with chat-ui interface.
When connected to Apify MCP Server the Tester MCP Client provides an interactive chat interface where you can:
The Apify MCP Client connects to a running MCP server over HTTP streamable (recommended) or SSE and it does the following:
/sse
).POST /message
.GET /sse
) that may include LLM output, and tool usage blocksLearn about the key features and capabilities in the Apify MCP Server Tutorial: Integrate 5,000+ Apify Actors and Agents Into Claude video
You can run the Tester MCP Client on Apify and connect it to any MCP server that supports SSE. Configuration can be done via the Apify UI or API by specifying parameters such as the MCP server URL, system prompt, and API key.
Once you run Actor, check the logs for a link to the Tester MCP Client UI, where you can interact with the MCP server: The URL will look like this and will be different from run to run:
INFO Navigate to https://......runs.apify.net in your browser to interact with an MCP server.
The Apify MCP client uses a modern and flexible approach for AI Agents monetization and pricing called Pay-per-event. You only need to have Apify account and you can use it, LLM provider API key is not required but you can supply it if you want to use your own LLM provider.
Events charged:
When you use your own LLM provider API key, running the MCP Client for 1 hour with 128 MB memory costs approximately $0.06. With the Apify Free tier (no credit card required 💳), you can run the MCP Client for 80 hours per month. Definitely enough to test your MCP server!
Browser ← (SSE) → Tester MCP Client ← (HTTP streamable or SSE) → MCP Server
We create this chain to keep any custom bridging logic inside the Tester MCP Client, while leaving the main MCP Server unchanged. The browser uses SSE to communicate with the Tester MCP Client, and the Tester MCP Client relies on HTTP streamable or SSE to talk to the MCP Server. This separates extra client-side logic from the core server, making it easier to maintain and debug.
https://tester-mcp-client.apify.actor?token=YOUR-API-TOKEN
(or http://localhost:3000 if you are running it locally).index.html
and client.js
are served from the public/
directory.GET /sse
.POST /message
.sseEmit(role, content)
The Tester MCP Client Actor is open source and available on GitHub, allowing you to modify and develop it as needed.
Download the source code:
git clone https://github.com/apify/tester-mcp-client.gitcd tester-mcp-client
Install the dependencies:
npm install
Create a .env
file with the following content (refer to the .env.example
file for guidance):
APIFY_TOKEN=YOUR_APIFY_TOKENLLM_PROVIDER_API_KEY=YOUR_API_KEY
Default values for settings such as mcpUrl
, systemPrompt
, and others are defined in the const.ts
file. You can adjust these as needed for your development.
Run the client locally
$npm start
Navigate to http://localhost:3000 in your browser to interact with the MCP server.
Happy chatting with Apify Actors!
The client does not support all MCP features, such as Prompts and Resource.
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