API and MCP

API access and webhooks are included in the Vystav plan. Set them up in Settings › , API and webhooks; an owner or administrator manages keys and webhooks.

API key

1. Under API keys, enter a Key label, such as the name of the app that will use it.
2. Select only the permissions the app actually needs.
3. Click Create key and copy the key immediately. It is shown only once; Vystav stores only its hash.

Revoke a key you no longer need or that may have leaked using Revoke. Apps using it will stop working.

invoices:read

Read invoices.

invoices:write

Invoice drafts, issuing them and recording payments.

contacts:read

Read contacts.

contacts:write

Create contacts.

products:read

Read the product catalogue.

expenses:read

Read received documents and expenses.

reports:read

Reports and summaries.

Interface

The API is REST with JSON at /api/v1. Send the key in the Authorization: Bearer nota_… header. An OpenAPI description of all endpoints is available at /api/v1/openapi.json.

Webhooks

A webhook sends a message to your chosen address whenever a selected event happens in Vystav: an invoice is created, issued, emailed, paid or becomes overdue; an expense is recorded; or a customer accepts a quote.

We sign each message using the vystav-signature header (HMAC-SHA256) with a signing key shown once when you create the webhook. If your address does not accept the message, we retry delivery with increasing intervals.

Claude through MCP

Claude and other apps supporting MCP (Model Context Protocol) work with your invoices, contacts and reports through an API key and can do only what you allow that key to do.

1. Create an API key. For questions, invoices:read, contacts:read and reports:read are enough. If Claude should prepare invoices and record payments, add invoices:write; for creating contacts, add contacts:write.
2. Under Claude (MCP), copy the server address. For an app that lets you supply a header with a custom connector, this address and the header containing your key are enough.
3. For Claude Desktop, copy the prepared configuration using Copy configuration. In Claude, open Settings › , Developer › , Edit Config and paste it into claude_desktop_config.json. Replace nota_… with your key and restart Claude. You need Node.js installed.

Through MCP, Claude can find invoices and contacts, prepare and issue an invoice draft, record a payment, create a contact, find a company in the register and show an overview and VAT summary. An invoice draft is not issued automatically; issuing is a separate step.