bexio-mcp

MCP server and typed TypeScript client for the bexio API — the Swiss business software for contacts, quotes, orders, invoicing, purchasing, accounting, banking, projects, time tracking and payroll.

• Complete: covers all 310 documented operations of the bexio API through 35 well-described MCP tools (enforced by a coverage test against the official OpenAPI spec).

• Reusable: the typed API client is a standalone entry point (bexio-mcp/client) with zero MCP dependencies — use it in any Node.js project.

• Safe: opt-in read-only mode, destructive-action annotations, tool-group filtering, and API errors mapped to actionable messages (expired token, missing scope, rate limit) instead of crashes.

• Robust: automatic retry on rate limits (honouring RateLimit-Reset), retries for transient GET failures, request timeouts, typed error hierarchy.

Quick start

1. Choose an authentication method

Option A — Personal Access Token (simplest, personal use): create a PAT at developer.bexio.com/pat. PATs have full access to your company data and expire after six months. Set it as BEXIO_API_TOKEN.

Option B — App workflow (OAuth 2.0 Authorization Code Flow, for apps and scoped access):

1. Create an app at developer.bexio.com and add http://127.0.0.1:33771/callback to its Allowed redirect URLs.

2. Reveal the Client ID and Client Secret under "App Details".

3. Authorize once — a browser opens for the bexio consent screen:

   BEXIO_CLIENT_ID=… BEXIO_CLIENT_SECRET=… npx bexio-mcp login

   Requested scopes are derived from the enabled tool groups (write scopes are dropped in --read-only mode); override with --scopes. Tokens land in ~/.bexio-mcp/tokens.json — treat that file like a password.

4. Start the server with the same BEXIO_CLIENT_ID/BEXIO_CLIENT_SECRET env (no BEXIO_API_TOKEN): it uses the stored tokens and auto-refreshes them, persisting the rotated refresh token on every refresh. With offline_access the session stays valid as long as it refreshes at least once a year.

bexio-mcp whoami prints the authenticated user; bexio-mcp logout deletes the stored tokens (and also revokes them at the identity provider when the app credentials are set).

2. Add the server to your MCP host

Claude Code

claude mcp add bexio --env BEXIO_API_TOKEN=<your-token> -- npx -y bexio-mcp

Claude Desktop / any MCP host (claude_desktop_config.json or equivalent):

{
  "mcpServers": {
    "bexio": {
      "command": "npx",
      "args": ["-y", "bexio-mcp"],
      "env": {
        "BEXIO_API_TOKEN": "<your-token>"
      }
    }
  }
}

That's it — ask your model to "list open bexio invoices", "create a quote for Muster AG", or "how many hours were tracked on project X this month?".

Using something else? There are copy-paste quick-starts for Cursor, VS Code, Windsurf, Gemini CLI, Codex CLI, Pi, Agno, OpenAI Agents SDK, Pydantic AI, LangChain/LangGraph, n8n, the Claude Agent SDK and more in docs/integrations.

Related MCP server: mcp-server-smallinvoice

Configuration

bexio-mcp --list-tools prints the tools that would be registered; --help shows usage.

Read-only mode

BEXIO_API_TOKEN=… BEXIO_READ_ONLY=true npx bexio-mcp

Write actions return an explanatory error without touching the API; tools that only write are hidden entirely. Recommended when you want analysis/reporting but no mutations.

Tool groups

contacts, sales, purchase, accounting, banking, items, projects, files, payroll, misc

BEXIO_TOOL_GROUPS=contacts,sales,items npx bexio-mcp

Tools

Tools are grouped per resource with an action argument; each tool's description documents every action and its required arguments.

Highlights:

• Full document lifecycle: create → issue → send/mark-as-sent → payments/reminders → PDF, for quotes, orders, deliveries and invoices — including converting quotes to orders/invoices and orders to deliveries/invoices.

• All seven position types (item, custom, text, subtotal, discount, pagebreak, sub-position) on quotes, orders and invoices via one generic bexio_document_positions tool.

• PDF and file downloads accept a save_path argument so large documents go to disk instead of the context window.

• Legacy search endpoints take search_criteria: [{ "field": "name_1", "value": "Muster", "criteria": "like" }], combined with AND.

Server-side & Docker

bexio-mcp serve-http runs the server on the streamable HTTP transport — no GUI, configuration only, with automatic token refresh. Two auth modes, combinable:

• Multi-user (pass-through): don't configure any server credentials. Every client sends its own Authorization: Bearer <bexio PAT or OAuth access token> header; each MCP session acts as that user against bexio, and nothing is stored server-side. Sessions without a token are rejected with 401.

• Shared identity (single-tenant): configure BEXIO_API_TOKEN or the app credentials — then sessions without their own bearer use the server's identity. This grants unauthenticated, full access to that bexio account to anyone who can reach the port. On non-loopback binds (including Docker) it therefore stays off until you explicitly set BEXIO_HTTP_SHARED_IDENTITY=true; publish the port to loopback or a private network only (-p 127.0.0.1:8722:8722).

Headless OAuth (no browser anywhere): obtain a refresh token once — either run bexio-mcp login on a workstation and copy ~/.bexio-mcp/tokens.json into the container volume, or seed via BEXIO_REFRESH_TOKEN. The server refreshes it on first use and persists the rotated tokens to BEXIO_TOKEN_STORE; a stale seed left in the environment is ignored once the store holds fresher tokens.

docker build -t bexio-mcp .            # or: docker pull ghcr.io/mydata-ag/bexio-mcp:latest

# Multi-user: clients authenticate themselves per request
docker run -p 8722:8722 bexio-mcp

# Single-tenant with app workflow + automatic refresh, tokens survive restarts.
# Note the explicit shared-identity opt-in and the loopback-only publish.
docker run -p 127.0.0.1:8722:8722 -v bexio-tokens:/data \
  -e BEXIO_CLIENT_ID=… -e BEXIO_CLIENT_SECRET=… -e BEXIO_REFRESH_TOKEN=… \
  -e BEXIO_HTTP_SHARED_IDENTITY=true \
  bexio-mcp

Connect any MCP client to http://host:8722/mcp (e.g. Agno: MCPTools(transport="streamable-http", url="http://host:8722/mcp"), with the bearer header for multi-user mode). GET /healthz serves Docker health checks.

Security notes: terminate TLS in a reverse proxy — bearer tokens must not cross networks in plain HTTP; the server binds 127.0.0.1 by default outside Docker; idle sessions are closed after 30 minutes and concurrent sessions are capped (503 past the limit); loopback binds validate the Host header against loopback values (DNS-rebinding protection) — behind a proxy, list your public hostname(s) in BEXIO_HTTP_ALLOWED_HOSTS; a bind-mounted /data must be writable by uid 1000 (prefer the named volume); env-passed secrets are visible via docker inspect — use your orchestrator's secret mechanism where available.

Using the client without MCP

The typed client is dependency-free (uses global fetch) and importable on its own:

import { BexioClient } from 'bexio-mcp/client';

const bexio = new BexioClient({
  token: process.env.BEXIO_API_TOKEN!,   // string or async () => string
  language: 'de',
});

The OAuth building blocks are exported too — BexioOAuth (authorization URL with PKCE, code exchange, refresh with rotation) and OAuthTokenProvider (auto-refreshing token source) from bexio-mcp/client, plus FileTokenStore and runLoginFlow from bexio-mcp:

import { BexioClient, BexioOAuth, OAuthTokenProvider } from 'bexio-mcp/client';
import { FileTokenStore } from 'bexio-mcp';

const oauth = new BexioOAuth({ clientId, clientSecret });
const provider = new OAuthTokenProvider(oauth, new FileTokenStore());
const bexio = new BexioClient({ token: provider.accessTokenProvider() });

// Typed resource APIs mirroring the bexio docs
const contacts = await bexio.contacts.search([{ field: 'name_1', value: 'Muster' }]);
const invoice = await bexio.invoices.createInvoice({ contact_id: contacts[0]!.id, positions: [/* … */] });
await bexio.invoices.issueInvoice(invoice.id);

// Escape hatch for anything else
const me = await bexio.http.get('/3.0/users/me');

Errors are typed: BexioApiError (with status, errorCode, body, plus isAuthError/isPermissionError/isNotFound/isRateLimit), BexioRateLimitError, BexioNetworkError, BexioConfigError.

Embedding the server in your own process:

import { BexioClient, createBexioMcpServer } from 'bexio-mcp';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

const server = createBexioMcpServer({
  client: new BexioClient({ token: myToken }),
  groups: ['contacts', 'sales'],
  readOnly: true,
});
await server.connect(new StdioServerTransport());

Development

npm install
npm run typecheck   # tsc --noEmit
npm test            # vitest (includes the API coverage gate)
npm run build       # tsup → dist/ (ESM + CJS + d.ts)

With just: just check runs the full gate, just docker-build builds the image.

Releasing

Releases are tag-driven: pushing vX.Y.Z triggers the release workflow, which verifies the tag against package.json, runs the full gate, pushes the multi-arch Docker image to ghcr.io/mydata-ag/bexio-mcp (latest, X.Y, X.Y.Z), creates the GitHub release with generated notes, and publishes to npm when the NPM_TOKEN secret is configured.

just bump minor   # bump package.json + src/version.ts, commit "Release vX.Y.Z"
git push          # let CI pass on main
just tag          # tag vX.Y.Z (verifies clean tree, main, pushed, version sync) and push it

See docs/ARCHITECTURE.md for the layering and module conventions. The API surface is pinned in tests/fixtures/operations.json (extracted from the official docs); tests/coverage.test.ts fails when bexio documents operations this package does not cover.

Notes & limitations

• The bexio API rate limit is per company; heavy parallel use of tools can hit 429s — the client waits and retries automatically.

• bexio deletes are permanent (no trash). Destructive tool actions are annotated and blocked in read-only mode, but be deliberate.

• Credit notes and a handful of business processes are not exposed by the bexio API itself (see their FAQ).

• This is an unofficial project; not affiliated with bexio AG.

License

MIT