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Public API Overview

The Fiskl public API lets you read and update your accounting data from outside Fiskl — through an AI assistant, an automation tool, or your own software. This overview explains the pieces and helps you pick the right starting point.

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Beta Notice: The API, Webhooks, and MCP server are currently in Beta. This means these tools are actively in development; stability is not fully guaranteed and endpoints may change without notice. We encourage you to use this period to familiarise yourself with the system, and we will notify all users once they reach general availability.

Start Here​

You do not need to be a developer to use the API. Choose the path that matches what you want to do.

I want to...Start with
Ask an AI assistant about my business, or have it create invoicesConnect Your AI Assistant
Have an AI tool build an automation or n8n workflow for meBuild an Automation with AI
See what data and actions are available before decidingWhat You Can Do with the API
Try a request in my browser without writing codeUse the Interactive API Docs
Write my own integration in codeMake Your First API Request

What the Public API Is​

The public API is a stable set of web endpoints under /v1 — for example /v1/clients and /v1/invoices. You send a request with a token, and Fiskl returns your company's data as JSON. Every request is authenticated and limited to what the token is allowed to do.

The full, interactive reference lives at api-docs.fiskl.com. There you can browse every endpoint, see example responses, and run real calls in the browser after pasting in an API key. This help section explains the concepts around that reference: how to get a token, how access is scoped, and how to receive events.

The Building Blocks​

These features work together. Most integrations use two or three of them.

Building blockWhat it isUse it when
API keysA token (fsk_…) you create for your own scripts and toolsYou are building your own integration or automation
Connected apps (OAuth)A registered app that other Fiskl users authorise to act on their behalfYou are building an app or connector for other people to use
AI assistant connection (MCP)A direct link between an AI assistant such as Claude and your Fiskl dataYou want to work with your accounts in conversation
API endpointsThe /v1 requests that read and change your dataAny time you read or update Fiskl data programmatically
WebhooksNotifications Fiskl sends to your system when something happensYou need to react to events such as an invoice being paid

A simple way to remember the difference between the token types: an API key is for your own access, a connected app lets someone else's app access a user's data with that user's consent, and an AI assistant connection is a connected app you authorise for yourself.

How Access Is Controlled​

Every request carries a token in the Authorization header, and Fiskl checks two things: that the token is valid, and that it is allowed to perform the action.

  • API keys use fine-grained permissions, such as invoice.read. You select these on a grid when you create the key, and you can only grant permissions you hold yourself.
  • Connected apps and AI assistants use coarser scopes, such as invoicing:read. The person authorising approves these scopes on a consent screen.

In both cases, a token can never do more than its owner can. If your permissions change, every token you created reflects that change immediately.

Sensitive actions are never available to any token, whatever you grant. These include managing team members, changing your subscription, creating API keys, and posting manual journals.

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The interactive endpoint reference at api-docs.fiskl.com always reflects the current API. Use it alongside these guides to see exact fields and example responses.

Guides​