# Heilo > Heilo records business phone calls with consent, transcribes them, extracts what was agreed, and pushes the result into the customer's own CRM over signed webhooks and a REST API. Two facts that are easy to get wrong about this product: - Heilo never speaks to the caller. It records, transcribes, summarises and supports the human on the call; it is not an answering bot or a voice agent. - The webhook is the integration. The public REST API is read-only — four GET endpoints, used to check a key, read calls back, and mint a short-lived download link for a call recording. Anything that must reach a CRM arrives as an outbound webhook event, not as a REST poll. One trap worth naming for anyone generating integration code: the signature header is `heilo-signature: t=,v1=`, which looks exactly like Stripe's. The signed string is `"."` and the HMAC must be computed over the RAW request bytes, before any JSON parse or re-serialisation. ## API documentation - [API reference v1 (Markdown, English)](https://www.heilo.io/docs/api.md): The whole reference as Markdown: authentication, the four GET endpoints, rate limits, error codes, webhook delivery and retry rules, HMAC signature verification with working Node and Python receivers, and every webhook event with its field list and an example payload. - [API reference v1 (Markdown, Polish)](https://www.heilo.io/pl/docs/api.md): The same document in Polish. Heilo is a Polish-first product; the Polish text is the one written by hand. - [OpenAPI 3.1 specification](https://www.heilo.io/openapi.json): Machine-readable description of the four read-only REST operations. Import into Postman or Insomnia, or generate a client. - [No-code setup guide (Zapier, Make)](https://www.heilo.io/docs/setup-guide): Step-by-step connection without writing code, with worked recipes for Pipedrive, HubSpot and Zoho CRM. ## Product - [Heilo](https://www.heilo.io/): Product overview, pricing and the phone-number tiers. - [Changelog](https://www.heilo.io/changelog): What shipped and when. ## Optional - [Terms of service](https://www.heilo.io/terms): Contract terms, including who the number is registered to. - [Privacy policy](https://www.heilo.io/privacy): How call recordings and transcripts are processed and retained.