ContaBridge

contabridge-mcp

An MCP server that moves bookkeeping between Spanish accounting programs and QuickBooks / Xero, built for AI agents that work for gestorías and accounting firms with many clients. It does not store any data between calls, and every result is deterministic.

Output files are returned as content and as content_base64. The base64 version is Windows-1252 with CRLF line endings (UTF-8 with BOM for CSV), which is what these programs import.

Charging works like this:

• A file that would be rejected (unbalanced, unreadable, missing columns) is refused before any credits are charged.
• A failure after charging is refunded.

Formats and sources

• A3: "Enlace contable de entrada. Descripción de registros" (Wolters Kluwer). Record type 0, format 5 (512 bytes) and format 4 (256 bytes). When reading, invoice records (types 1, 2 and 9) are skipped and reported in a warning.
• ContaPlus: "Protocolo de comunicación de programas de gestión con ContaPlus" (Sage, 2023). Writes Asien, Fecha, SubCta, Contra, Concepto, Documento, MonedaUso=2, EuroDebe and EuroHaber. The fixed-width ASCII variant (32 fields) uses the same layout as the open-source BulmaGés exporter.
• QuickBooks Desktop IIF: GENERAL JOURNAL transactions (!TRNS/!SPL/!ENDTRNS, tab separated). Debits are positive and credits negative, so the TRNS amount is minus the sum of its SPL lines. Other IIF lists (accounts, customers) are skipped with a warning.
• QuickBooks Online: "Import journal entries" CSV with Journal No., Journal Date, Account Name, Debits, Credits, Description, Name.
• Xero: "Import a manual journal" template (*Narration, *Date, Description, *AccountCode, *TaxRate, *Amount, tracking). Lines with the same Narration and Date form one journal. xero_tax_rate sets the TaxRate as named in that organisation (UK No VAT, AU BAS Excluded, NZ No GST, US Tax Exempt).
• QuickBooks and Xero dates follow date_style: mdy (default for QuickBooks), dmy (default for Xero) or iso. Amounts use a decimal point, and a comma is always read as a thousands separator. Their accounts are names or codes, so they are validated against their own chart, not the PGC. Use account_map to translate them when converting to or from A3/ContaPlus.
• CSV: columns are detected in Spanish and English (fecha, cuenta, debe, haber, importe+d/h…), or set with column_map. A file without an entry number is grouped into entries by accumulating lines until they balance.

Install

All you need is your KeyFlint license (LIC-...). The gateway URL, its public key and the checkout link have defaults.

Claude Desktop, one click: download contabridge-mcp-X.Y.Z.mcpb from the latest release, double-click it and paste your license. No terminal, no JSON.

Claude Code:

claude mcp add contabridge -e KEYFLINT_LICENSE=LIC-... -- uvx contabridge-mcp

Cursor, Windsurf, Claude Desktop (JSON):

{  "mcpServers": {    "contabridge": {      "command": "uvx",      "args": ["contabridge-mcp"],      "env": { "KEYFLINT_LICENSE": "LIC-..." }    }  }}

Optional: KEYFLINT_URL, KEYFLINT_PUBLIC_KEYS (fetched from the gateway and cached in ~/.keyflint/keyring.json when unset), KEYFLINT_CHECKOUT_URL.

Hosted mode: CONTABRIDGE_TRANSPORT=http contabridge-mcp --http (license per request, Authorization: Bearer LIC-...).

Tuning: CONTABRIDGE_PRICES (convert_journal=3,bank_to_journal=5), CONTABRIDGE_MAX_BYTES.

Visual cards (MCP Apps)

In Claude, ChatGPT, VS Code and Goose every paid tool and credits_balance renders as an interactive card in the chat: credit balance with a refill bar and a buy button, or a result summary (key figures, issues, table preview and credits charged). It is the ui://contabridge/card.html resource, self-contained with no network access. Other clients keep getting the same JSON as before.

Claude skill

skills/contabridge/SKILL.md (zipped in distribution/contabridge-skill.zip) tells the agent which tool to use, which account length to ask for, and how to save the file.

Tests

pip install -e '.[test]' && pytest

The tests use a fake KeyFlint gateway and locally signed licenses, so they need no network. A3 and ContaPlus layouts are checked position by position against the official specifications.

License

Business Source License 1.1. Source available; production use needs a KeyFlint license (or must be non-commercial). Each version becomes Apache 2.0 four years after release. See LICENSE.