character

This is a tool for various manipulations on characters, as characters rather than full strings, to show names, encodings and more.

The tool is structured as a top-level command, options, and sub-commands which can do different things. Many sub-commands will take a -v verbose option, which gives more detail in a pretty-printed table.

$ character help
[... lists all available sub-commands ...]
$ character version
[...]
$ character search check
[... table of results; search is convenience alias ...]
$ character name ✓
CHECK MARK
$ character named -h
[...]
$ character named 'CHECK MARK'
✓
$ character named -j CHECK MARK
✓
$ character named -v/ check
[... table of results of substring search ...]
$ character browse -b 'Alchemical Symbols'
[... table of results; browse is always a table ...]
$ character transform fraktur Hello world
ℌ𝔢𝔩𝔩𝔬 𝔴𝔬𝔯𝔩𝔡
$ character transform scream Hello world
A̰áăăå ȁåȃăa̱
$ character transform scream --decode \
    $(character transform scream Hello world)
Hello world
$ character named -Jj CHECK MARK
{"characters":[{"display":"✓","name":"CHECK MARK","hex":"2713",...}]}
$ character named -1c 'INFORMATION DESK PERSON' \
    'EMOJI MODIFIER FITZPATRICK TYPE-5'
💁🏾

In the last example, note that -c copies to clipboard; using -vc shows the results in a table but copies only the characters to the clipboard. Without --oneline (-1) each non-verbose character is shown on its own line. In this example we're using an emoji modifier which needs to immediately follow the modified character, so -1c should show you the same thing that is copied to the clipboard where -c on its own would show you the individual parts while copying the modified/combined whole to the clipboard.

Use -J / --json for machine-readable output — this is the most reliable format for scripting and agent consumption (but consider MCP invocation).

Licensed under a MIT-style license.
Accumulated licenses of all dependencies are available too.
Patches welcome.

Agent and MCP support

The agent sub-command tree has commands designed for AI coding agents and other automated tooling. All agent output is stable, machine-readable JSON. AIs should see AGENTS.md for full tool schemas and usage patterns.

character agent mcp starts a Model Context Protocol stdio server. This allows character to act as a co-process providing Unicode domain knowledge.

(Disclosure: Claude was used to implement the MCP support.)

(Added in v0.10.0)

Schema stability: The MCP tool schemas (parameter names, types, and response shapes) may change incompatibly across any release, including patch versions. Clients must discover schemas at runtime via the MCP tools/list method rather than hard-coding parameter knowledge.

Registering as an MCP server

Claude Code

claude mcp add --scope user --transport stdio character -- character agent mcp

This registers the agent as available for all Projects; drop the --scope user to only make available to this specific project.

The server returns an instructions field in its MCP initialize response, which Claude Code uses to discover the Unicode tools automatically via Tool Search — no additional configuration is needed for basic usage.

Installing the custom slash command (optional): the file extra/character-unicode.md provides a deeper reference — a tool-routing decision table, the full property field reference, and advanced tips. Install it as a custom slash command for on-demand access:

# from the character source tree
mkdir -pv ~/.claude/commands
cp -v extra/character-unicode.md ~/.claude/commands/./

Once installed, type /character-unicode in a Claude Code session to load the extra guidance into context. The server's instructions text references the command, so Claude can load it when detailed guidance is needed.

Other MCP clients

Any client that supports the MCP stdio transport can launch character agent mcp as a subprocess. The server speaks JSON-RPC 2.0 with newline-delimited framing (one JSON object per \n-terminated line). Clients that support the MCP instructions field will receive discovery guidance and key usage patterns automatically.

Documentation

| File | Audience | | -------------------------------- | ----------------------------------------------------------------------------------- | | AGENTS.md | AI agents — tool schemas, example invocations, output formats | | CODE_GUIDE.md | Developers — package map, reading order, data flow, protocols | | extra/character-unicode.md | AI agents — tool-routing table, property field reference, Claude Code slash command |

Building

Requires Go 1.24 or newer.

Install without cloning:

go install github.com/philpennock/character@latest

Or clone and build locally:

git clone https://github.com/philpennock/character.git
cd character
go build

Unicode data and entity tables are compiled in. To regenerate them after updating source data files (e.g. for a new Unicode version):

go generate ./...

WASM

Run: ./util/make_wasm.sh

A directory wasm will be created; the character binary will be compiled into there as main.wasm; a supporting HTML page will be copied in, as well as the Golang wasm_exec.js support page.

Run a web-server which serves up the content of the wasm/ directory and see how it works. We should perhaps have a way to default to verbose mode (for tables) to better support this use-case.

SECURITY NOTE: Note: to have tables work, I switched from innerText to innerHTML, but this early proof-of-concept is not escaping output to be proof against HTML injection attacks. In particular, an unknown command will be echo'd back in the error message, as is fairly common for Unix CLI tools. We could use a separate output area for errors and use innerText for that, but that doesn't solve, eg, the output of transform commands which deliberately make reversible changes to input and displays it.

So don't put this up somewhere public, at least not in a domain with access to any cookies or other credentials worth stealing. But it's a useful toy to explore with. Well, it was for me: "My First WASM".

Table packages

Versions prior to v0.9.0 supported multiple table packages for rendering tables to the terminal. With v0.9.0, we dropped support for all table packages other than by own go.pennock.tech/tabular, support for which was added in v0.1.0.

Alternatives

uni by Martin Tournoij: https://github.com/arp242/uni — go install arp242.net/uni/v2@latest
unicode (Debian/Ubuntu): apt install unicode — command-line Unicode database query tool
unipicker by Jeremy Janzen: https://github.com/jeremija/unipicker — interactive console Unicode character picker with clipboard support

Character

Install / Use

README