REST API & DATEV Export

Anyone working seriously with invoices eventually wants out of the manual click routine. Figures should flow automatically into their own software, the tax advisor should get the postings without retyping, and other systems should learn when an invoice was paid. For exactly this, this tool bundles three building blocks: a REST API, outbound webhooks and the DATEV export.

The REST API is scoped, meaning it has fine-grained permissions. You create API keys and grant specific rights: "read sales" (sales:read) to fetch invoices, customers, articles and payments, "write sales" (sales:write) to create drafts, finalize and record payments, and "manage webhooks" (webhooks:manage) for webhook subscriptions. Each key shows its prefix, when it was last used, and can be revoked at any time. So an integration key for an accounting tool stays limited to exactly the rights it needs.

Outbound webhooks deliver events to your own URL in real time. When an invoice is finalized or a payment is recorded, the system sends a signed message to your endpoint. The HMAC signature lets you verify the authenticity of every delivery so nobody can inject forged events. That way you react to business events automatically instead of polling.

The DATEV export is the centrepiece for working with your tax advisor. From your invoices for a period, the tool produces a DATEV-compatible posting batch in the EXTF format that your firm can import directly into DATEV Kanzlei-Rechnungswesen. You provide the advisor number (seven digits), the client number (five digits), the start of the fiscal year and the chart of accounts - SKR03 or SKR04 - and the export maps revenue and debtor accounts by the canonical rules.

The validation is strict, because DATEV is strict. Advisor and client numbers must have exactly the right digit count, the end date must come after the start date. Small format mistakes otherwise cause import problems at the firm later - better that the tool catches them immediately, with clear messages instead of cryptic DATEV errors.

This tool is for everyone who wants to scale their accounting: freelancers with many invoices, small businesses with their own tooling, and everyone who wants to keep their tax advisor happy. Together with the API Playground to try the endpoints and Scripts to process results, it becomes an automation chain that noticeably reduces manual bookkeeping.