Plunger
A lightweight native API testing tool written in Rust that provides unified observability for both human and AI agent operations. It proxies agent API calls through the MCP protocol, displays call details in real time, and includes built-in token-hiding and placeholder security mechanisms.
Timeline (last 90 days)
Plunger's responses are presented as a collapsible, searchable tree structure, and support directly copying the JSON path of a given node.
Plunger's three entry points (GUI, CLI, MCP) share the same set of saved requests, the same set of variables, and the same history.
Plunger's history marks whether each request came from the CLI or from MCP.
When a variable is undefined, Plunger refuses to send the request and clearly states which variable is missing, rather than sending placeholders such as {{token}} to the server as-is.
When an Agent sends a request via the command line or MCP, it can ask only for the fields it needs, achieving precise value retrieval rather than a full return.
Plunger allows multi-step API calls to be saved as a workflow, which an Agent can run through the entire chain in a single call, while the user can watch the flow light up step by step in the interface.
Plunger claims that every action of an Agent is written to a tamper-evident log, and that credentials in request headers, query strings, and request bodies are masked before they touch disk.
Plunger is an open source project under the MIT license.
Plunger can be installed via pip or homebrew, and running `plunger install` also connects it to an Agent.
Plunger is an HTTP client designed for both humans and AI Agents, offering three entry points: a graphical window, a command line (CLI), and an MCP server.
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All Facts (18)
Plunger's responses are presented as a collapsible, searchable tree structure, and support directly copying the JSON path of a given node.
50%UnverifiedPlunger's three entry points (GUI, CLI, MCP) share the same set of saved requests, the same set of variables, and the same history.
50%UnverifiedPlunger's history marks whether each request came from the CLI or from MCP.
50%UnverifiedWhen a variable is undefined, Plunger refuses to send the request and clearly states which variable is missing, rather than sending placeholders such as {{token}} to the server as-is.
50%UnverifiedWhen an Agent sends a request via the command line or MCP, it can ask only for the fields it needs, achieving precise value retrieval rather than a full return.
50%UnverifiedPlunger allows multi-step API calls to be saved as a workflow, which an Agent can run through the entire chain in a single call, while the user can watch the flow light up step by step in the interface.
50%UnverifiedPlunger claims that every action of an Agent is written to a tamper-evident log, and that credentials in request headers, query strings, and request bodies are masked before they touch disk.
50%UnverifiedPlunger is an open source project under the MIT license.
50%UnverifiedPlunger can be installed via pip or homebrew, and running `plunger install` also connects it to an Agent.
50%UnverifiedPlunger is an HTTP client designed for both humans and AI Agents, offering three entry points: a graphical window, a command line (CLI), and an MCP server.
50%UnverifiedPlunger is completely free and open source
50%UnverifiedPlunger can be installed via the command pip install plunger-cli
50%UnverifiedPlunger puts human operations and AI Agent operations under unified observation and management in the same interface, where users can manually send requests while AI Agents call APIs through MCP
50%UnverifiedPlunger exists as an MCP Server, proxying requests that Agents make to target APIs, capturing and displaying all call details
50%UnverifiedPlunger displays every API call made by the AI Agent in real time as a Live stream in the interface
50%UnverifiedPlunger hides real tokens by replacing actual keys with placeholders at the storage layer, so that request records do not write plaintext keys to disk
50%UnverifiedPlunger supports re-running any call made by the Agent via the CTRL-ENTER shortcut
50%UnverifiedPlunger is a lightweight native API testing tool written in Rust, serving both the developer themselves and the AI Agent collaborating with the developer
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