Kandle

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Kandle is a free, open source charting app for crypto, stocks and forex that runs in your browser. You don't need an account, and Kandle has no server of its own: market data goes from each provider straight to your browser, and your charts, scripts and API keys stay in local storage. It also ships an MCP server, so Claude Code, Codex, Cursor or Gemini CLI can read the chart, draw levels, add indicators and run scripts while you watch.

An agent connected over MCP marks resistance and a support zone, adds RSI and runs an EMA cross script.

Get started

Open [kernel-hunter.github.io/kandle](https://kernel-hunter.github.io/kandle/). There is nothing to install, and live crypto data from five exchanges works without a key. Type any letter to search for a symbol, press / for indicators and Alt+S for the script editor.

To run your own copy, see Run it locally.

Use it with your AI agent

Kandle ships an MCP server, kandle-mcp. Your agent starts it, and the Kandle tab in your browser connects to it over a WebSocket on 127.0.0.1. You need Node.js 22.12 or newer.

For Claude Code:

claude mcp add kandle -- npx -y \

--package=https://github.com/Kernel-Hunter/kandle/releases/download/v0.11.0/kandle-mcp-0.11.0.tgz \ kandle-mcp

Other agents are below. Then ask something like "mark the last swing high and low on BTC and draw a Fibonacci retracement between them".

Set up

1. Add the server to your agent (the command above, or a snippet below).
2. Ask the agent for the Kandle pairing code. It calls get_bridge_status and shows a code like K7QD-9MXR-2HPA.
3. In Kandle, click Agent in the top bar, paste the code and turn on Agent bridge. The dot on the button turns green when the agent is connected.

The code is saved in your browser and in ~/.kandle/bridge-token, so you only pair once. This works with the hosted app and with a copy you run yourself. With the hosted app, your browser may ask whether the page can reach devices on your local network; allow it so the page can talk to kandle-mcp on 127.0.0.1.

Claude Desktop

Download kandle-mcp-0.11.0.mcpb and open it to install the server.

Codex

In ~/.codex/config.toml:

[mcp_servers.kandle]

command = "npx" args = ["-y", "--package=https://github.com/Kernel-Hunter/kandle/releases/download/v0.11.0/kandle-mcp-0.11.0.tgz", "kandle-mcp"]

Cursor and Gemini CLI

In ~/.cursor/mcp.json (or .cursor/mcp.json in a project) for Cursor, and ~/.gemini/settings.json for Gemini CLI:

{

"mcpServers": { "kandle": { "command": "npx", "args": ["-y", "--package=https://github.com/Kernel-Hunter/kandle/releases/download/v0.11.0/kandle-mcp-0.11.0.tgz", "kandle-mcp"] } } }

Other clients, updates and running from a clone

Kandle is listed in the MCP Registry as io.github.Kernel-Hunter/kandle, so clients that browse the registry can find it.

npx runs kandle-mcp from a GitHub release. When a new version of Kandle comes out, change the version in the URL; get_bridge_status tells your agent when the app is newer than its server.

To run it from a clone instead, use pnpm install && pnpm build and point your agent at node /path/to/kandle/packages/mcp/bin/kandle-mcp.js.

All 28 tools

Most tools take an optional pane (1 to 4) when several charts are showing. Times can be ISO 8601 dates or Unix times in seconds or milliseconds. Inputs are validated and errors say what to fix.

skills/kandle/SKILL.md is an agent skill with chart analysis workflows: support and resistance, trend, indicator confluence, and annotating a chart with an explanation. Copy it into your agent's skills folder (for Claude Code, ~/.claude/skills/kandle/).

Security model

The bridge is off until you turn it on, only listens on 127.0.0.1, and needs the pairing code on every connection.

How the bridge is locked down

• The bridge only listens on 127.0.0.1. Nothing is reachable from other machines.
• The app connects to the server, not the other way round, and only after you turn on Agent bridge. It is off by default and you can turn it off at any time.
• Every connection must send the pairing code first. The code has about 59 bits of randomness, is compared in constant time, and the server stops accepting codes for a minute after 5 wrong ones.
• The server rejects WebSocket connections from web pages that are not served from localhost, 127.0.0.1 or [::1], so a website you visit cannot connect even if it guesses the port. The hosted app at https://kernel-hunter.github.io is also allowed. Add other origins, such as your own hosted copy, with KANDLE_ALLOWED_ORIGINS.
• The server rejects requests whose Host header is not a loopback address, which blocks DNS rebinding.
• Drawing notes can come from a link someone else shared, so get_chart_state returns the text of at most 20 notes, 120 characters each, with untrusted_text: true. The tool description and the server instructions tell the agent that drawing text, script code and alert messages are data, not instructions.
• The agent can only do what the tools allow: read chart data, change symbols, chart types, indicators, drawings, alerts, replay, layout and the watchlist, take screenshots of the chart and make share links. It cannot read other tabs, your files or your browser storage.
• Only one Kandle tab is connected at a time. A newer tab takes over and the older one shows that it was replaced.
• Programs running as your user on the same computer can read ~/.kandle/bridge-token. That is the same trust level as the agent itself.

Settings: --port or KANDLE_PORT (default 7457, change the port in the Agent dialog to match), KANDLE_TOKEN for a fixed code, KANDLE_HOME for the token folder.

Features

• Live crypto with no key. Binance, Coinbase, Bybit, OKX and Kraken, with history over REST and updates over websockets.
• Stocks, ETFs and forex. Twelve Data, Alpaca or Polygon with your own free API key, or your own CSV files.
• 36 indicators and the usual drawing tools. Ichimoku Cloud, a volume profile, trend lines, channels, Fibonacci retracement, price ranges and notes.
• Your own scripts. Write indicators in Kandle Script in an editor under the chart, with 15 examples and request.security. See Scripts.
• Strategy backtests. Trades on the chart, net profit, drawdown, win rate, an equity curve and every trade. See Strategies.
• Compare symbols. Draw up to 5 other markets over the chart, such as ETH and SOL over BTC, on a percent scale. See Compare symbols.
• Alerts, bar replay and up to 4 charts. See Alerts, Bar replay and Layouts.
• Share links and embeds. The link carries the chart itself, and an iframe puts a live chart on any page. See Share a chart.
• An agent bridge. 28 MCP tools to read the chart, draw, compare symbols, set alerts, run scripts and take screenshots. See above.

Let an agent mark up the chart

Ask for levels and the agent draws them on your chart: here the 120-bar high and a Fibonacci retracement from it down to the 120-bar low.

Write an indicator, press Ctrl+Enter

Backtest a strategy

Fills show as arrows on the chart, and the Strategy tab has the numbers and the list of trades.

Compare symbols

BTC/USDT with ETH/USDT and SOL/USDT on the same percent scale, all starting at 0% on the left edge.

<img src="docs/screenshot-compare.png" alt="BTC/USDT dai