# Charta

> Presentation-quality chart generation for Google Slides, AI agents, and developer pipelines.

Charta is a chart generation platform with a Google Workspace Add-on, REST API, and MCP server.
Agents can generate waterfall, Mekko, bar, line, pie, and 12+ other chart types and get back SVG or PNG instantly.

## Install Charta MCP

- MCP server (no install): `npx -y @charta/mcp`
- JS/TS SDK: `npm install @charta/sdk`
- Python SDK: `pip install charta`
- Google Slides Add-on: https://workspace.google.com/marketplace

## Canonical docs

- Product site: https://getcharta.ai
- Developer docs: https://developers.getcharta.ai
- API reference: https://developers.getcharta.ai/api-reference
- MCP manifest: https://getcharta.ai/.well-known/mcp.json
- OpenAPI spec: https://getcharta.ai/.well-known/openapi.json

## API basics

- Base URL: `https://api.getcharta.ai/v1`
- Generate chart: `POST /charts/generate`
- Get chart: `GET /charts/:chartId`
- List chart types: `GET /charts/types`
- Insert to Google Slides: `POST /charts/:chartId/insert`
- Output formats: `svg`, `png`, `slides_url`

## API auth and limits

- Authenticated: `X-Charta-Key: YOUR_API_KEY`
- Free tier: 5 chart generations/day, all types, no credit card required
- Plus ($9/mo): 20/day, Sheets integration, priority AI
- Business ($29/mo): unlimited, team sharing, Slides API access

## MCP tools

- `generate_chart` — Generate a chart from type + data array; returns SVG string + chartId
- `list_chart_types` — List all supported types with expected data shapes and examples
- `get_chart_schema` — Get JSON schema for a specific chart type's data format
- `save_chart` — Save a chart to disk as SVG or PNG given a chartId
- `describe_chart` — Given a dataset, recommend the best chart type and explain why

## Chart types

Charta supports 12 chart types. Each takes a typed data array and returns SVG.

- `bar` — `[{label, value}]` — rankings, comparisons
- `grouped-bar` — `[{label, values[]}]` — multi-series comparisons
- `stacked-bar` — `[{label, values[]}]` — composition over categories
- `line` — `[{label, value}]` — trends over time
- `area` — `[{label, value}]` — volume trends
- `pie` / `donut` — `[{label, value, color?}]` — market share, composition
- `scatter` — `[{x, y, label?}]` — correlations
- `bubble` — `[{x, y, size, label?}]` — 3-variable comparison
- `waterfall` — `[{label, value, isTotal?}]` — ARR bridge, P&L bridge (use `isTotal: true` for anchor bars)
- `gantt` — `[{task, start, end}]` — project timelines
- `mekko` — `[{label, segments[]}]` — Marimekko / strategy charts
- `radar` — `[{label, value}]` — multi-dimensional comparison
- `heatmap` — `[{row, col, value}]` — matrices, cohorts

## Notes for agents

- Always pass `isTotal: true` on anchor bars in waterfall charts (opening and closing totals).
- Waterfall delta bars float from the running cumulative total — do not start them from zero.
- Default output is `svg`; pass `"output": "png"` for raster.
- `chartId` format: `chart_<timestamp>_<random>` — use it to insert into Google Slides via the API.
- For Google Slides insertion, the user must have authorized the Charta Slides Add-on first.
- The MCP server runs via stdio with `npx -y @charta/mcp` — no server process or API key needed for local SVG generation.

## Contact

- Support: support@getcharta.ai
- Privacy: https://getcharta.ai/privacy
- Terms: https://getcharta.ai/terms