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Lexware Office is a cloud accounting platform widely used by SMEs, freelancers, and accounting firms in Germany. Rebranded from lexoffice to Lexware Office in May 2025, it covers invoicing, expense tracking, contacts, and tax reporting. The public API is available on the XL plan only. Deeper accounting functionality requires Partner API access, which involves a bilateral qualification process with the Lexware team.
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Two API Tiers: Public API on XL Plan Only, Partner API Requires Bilateral Qualification
The Lexware Office public API is limited to XL plan users, the highest subscription tier. For deeper accounting functionality, the Partner API requires a qualification process with Lexware during which your product and use case are reviewed. Maesn is a qualified Lexware Partner and supports both API tiers, allowing your integration to serve customers on all relevant plans without requiring your own qualification process.
Optimistic Locking via Version Field: Every Update Requires the Current Resource Version
Lexware Office uses optimistic locking on all resources. Every update request must include the current version field of the resource. If another process has modified the same record in the meantime, the API returns a 409 Conflict error and the update must be retried with the refreshed version. Maesn handles version tracking and conflict retry logic automatically, so your integration never produces stale-version failures.
Multi-Step Workflows for Single Operations: Up to Four API Calls to Complete One Accounting Action
In Lexware Office, some single accounting operations require multiple sequential API calls. Attaching a file to a transaction, for example, requires creating the transaction, updating the financial account, uploading the file, and linking it using the returned reference. Maesn combines these multi-step sequences into single unified API operations, so your integration handles them as one call.
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Why companies choose Maesn
3 Reasons Why It Is Better To Integrate Lexware Office API With Maesn
Secure & Compliant
We have a strong relationship to Lexware Office. This ensures that the Maesn API is always up-to-date and any maintenance is covered on our end.
Common Data Model
We provide a clean, unified data model that abstracts away system-specific quirks, so teams can build reliable integrations without dealing with ERP-specific complexity or workaround-heavy implementations.
Lexware Office Sandbox
We provide you with everything you need, so you can focus on what counts.
Lexware Office, formerly known as lexoffice, is a cloud accounting platform for SMEs and freelancers in Germany. It was rebranded in May 2025. It covers invoicing, expense management, contacts, and German tax reporting including VAT returns. The public API is available on the XL plan; the Partner API requires bilateral qualification with Lexware.
The main challenges are navigating the two-tier API model where the public API is restricted to XL plan users, obtaining Partner API qualification for deeper accounting features, handling optimistic locking with version fields on every update, managing a rate limit of 2 requests per second per tenant, and executing multi-step API sequences for single accounting operations.
The public API is available to all XL plan users and covers standard endpoints including contacts, invoices, and documents. The Partner API requires a bilateral qualification with Lexware and provides access to deeper accounting functionality including voucher management and financial accounts. Maesn is a qualified partner and supports both tiers.
Optimistic locking means that every resource in Lexware Office includes a version field. When you update a resource, you must include the current version number in your request. If another process has modified the resource since you last read it, the API returns a 409 Conflict error. You must re-fetch the resource, get the new version number, and retry the update. Maesn handles this automatically.
A direct Lexware Office integration requires navigating two API tiers, obtaining Partner API qualification for advanced features, handling optimistic locking on every write operation, respecting a 2-request-per-second rate limit, and sequencing multiple API calls for single accounting actions. Maesn handles all of this through a single unified API.
Frequently Asked Questions About Lexware Office Integration
