Spoold is a free, privacy-first developer toolbox. Paste into the Magic Box and it detects JSON, HTML, JWT, curl, OpenAPI, CSV, timestamps, and more—then suggests the best tool. You can also browse the full catalog by category. No sign-up is required.

Is Spoold free to use?

Yes. Core tools are free. Heavy work runs in your browser so your payloads are not processed on Spoold servers for formatting, decoding, and similar utilities.

Is my data safe with Spoold?

Tool processing for supported client-side utilities happens in your browser. Encrypted share links are designed so only people with the link can read the payload. Review the Privacy Policy for details on local storage, analytics, support, and third-party services.

What tools are available?

Spoold ships 86+ tools including JSON formatter and diff, JSON Schema validation, YAML and TOML converters, HTML and Markdown preview, JWT decode and sign, OpenAPI/Swagger viewer with curl, GraphQL formatter, curl to code and curl compare, certificate viewer, CSV preview, regex tester, Mermaid, code editor, LLM token utilities, QR codes, and many encoding and text utilities.

Yes. Spoold uses optional support and in-layout promotions for its own tools instead of third-party ad placements. You can support development from the Support Spoold page.

Can I use keyboard shortcuts?

Yes. Press Cmd or Ctrl+K to open tool search, use / from the homepage, and use per-tool shortcuts (shown in the UI) such as jj for JSON and hh for HTML where configured.

Spoold

Paste. Detect. Do.

Paste a Cursor or Claude mcp.json, or a tools/list response. Servers, commands, and tool input schemas stay in the browser.

filesystem

stdio

npx -y @modelcontextprotocol/server-filesystem /Users/me/projects

ROOT=••••

docs

http

https://example.com/mcp

MCP Inspector — Read mcp.json and Tool Schemas

The MCP inspector reads a Model Context Protocol config or a tools/list payload and shows servers, commands, environment keys, and each tool's input schema. It runs in your browser.

Back to the inspector

What is this tool?

Cursor, Claude Desktop, and other agents store MCP servers in mcp.json under mcpServers. Each entry is either a local stdio process (command plus args) or a remote URL. A tools/list response is the other half: the tools that server exposes, with JSON Schema for the arguments.

Why use it

See every server, its transport, and the exact command line without opening the JSON by hand.
Check which environment variables a server expects. Values stay hidden until you choose Show env.
Read a tool's required fields before you write a prompt or a client call.
Nothing is uploaded. History and share only keep the text you pasted, so do not share a file that contains live tokens.

How to use

Paste mcp.json or a tools list. The Config and Tools list chips load samples.
For a config, read each server card: stdio command, HTTP URL, and env keys.
For tools, pick a name chip and read the property list plus the raw input schema.
Use Share or History when you want to come back to the same payload.

Config vs tools/list

A config answers "what process will start?" A tools list answers "what can the model call?" They are different documents. If a server fails to connect, check the command and args here, then ask the client for tools/list and paste that to confirm the schema the agent will send.

Related: MCP inspector guide.

FAQ

Where is mcp.json?

Cursor uses a project or user MCP config. Claude Desktop uses claude_desktop_config.json with the same mcpServers shape. Paste either one.

Does this start the server?

No. It only parses the JSON. It does not run commands or call URLs.

Why are env values hidden?

Configs often hold API keys. Show env when you need the value. Do not share or publish a config that still has production secrets.