# PeriodGuard

> Who changed your books, and when.

PeriodGuard keeps a full history of every change to your accounting records: who made it, when, and every value before and after. When anything changes in a month you have already closed, it emails you and your accountant. It only reads your books, never changes them.

## The feature: Change history

Returns the changes PeriodGuard found in the businesses connected to your account: the record, what kind of change, when, who made it (from the accounting system’s own history), every field’s value before and after, and whether the record is dated in a closed period. Filter by business, record type, dates, person, closed periods only, or a word.
- Input: A JSON object, every field optional: `businessId`, `recordType` (invoice, credit-note, payment, overpayment, prepayment, bank-transaction, bank-transfer, manual-journal, contact, account), `from` and `to` (YYYY-MM-DD), `closedOnly` (true or false), `user`, `search`, and `limit` (1 to 500, default 100).
- Output: A JSON object with `businesses` (id, name, status, closed-through date, last snapshot), `changes` (newest first; each with its business, record, change, times, record date before and after, closed period, who and the fields before and after), `total` and `truncated`.
- Endpoint: POST https://periodguard.com/api/v1/changes (JSON in, JSON out)
- Auth: Authorization: Bearer <api key> (keys are created by a signed-in person at https://periodguard.com/app/api-keys)
- Read only: businesses are connected and disconnected by a signed-in person in the web app; the API reads their change history
- Send x-usage-source: agent so usage is attributed to agents (does not change the price)

## Prices

- Free tier: 1 business, the last 30 days of history, 100 API and agent queries per calendar month (UTC), no card
- Business: $19/month or $190/year; 1 business, every change kept, 2,000 API and agent queries/month, 3 API keys
- Practice: $99/month or $990/year; 10 businesses, every change kept, 10,000 API and agent queries/month, 5 API keys
- Practice 50: $349/month or $3,490/year; 50 businesses, every change kept, 50,000 API and agent queries/month, 10 API keys
- Pay as you go for API and agent queries after a paid plan's allowance is used: $0.01 per query (usage event "change_query")
- Refunds: any charge within 14 days, no questions asked

## Machine-readable

- OpenAPI 3.1: https://periodguard.com/api/v1/openapi.json
- Product description (JSON): https://periodguard.com/.well-known/product.json
- MCP server: see https://periodguard.com/docs/agent-access (one tool, "changes", same schema as the API)

## Documentation

- https://periodguard.com/docs/getting-started
- https://periodguard.com/docs/change-history
- https://periodguard.com/docs/data-and-security
- https://periodguard.com/docs/api-keys
- https://periodguard.com/docs/agent-access
- https://periodguard.com/docs/billing
- https://periodguard.com/docs/refunds

## Policies

- Terms: https://periodguard.com/legal/terms
- Privacy: https://periodguard.com/legal/privacy
- Refunds: https://periodguard.com/legal/refunds
- Accessibility: https://periodguard.com/legal/accessibility
- Support: support@tenhatch.com