# flexEngage API Documentation

> flexEngage's public APIs for digital receipts, event webhooks, and email validation. Each API exposes an OpenAPI 3 specification and a Markdown companion generated from that specification, so coding agents can ingest accurate endpoint, parameter, and schema information without rendering JavaScript.

## Overview

- [Index](https://docs.flexengage.com/index.html): Landing page linking all APIs.

## Receipts API

The Receipts API powers digital receipt notifications and dynamic printed offers for in-store transactions.

- [Markdown companion](https://docs.flexengage.com/receipts-api.md): Start here — every endpoint, parameter, and schema as plain Markdown, with ready-to-copy curl/Java/C#/Python request samples.
- [OpenAPI spec (YAML)](https://docs.flexengage.com/receipts-api.yaml): Canonical machine-readable OpenAPI 3 spec; use for exact schemas and codegen.
- [Interactive docs](https://docs.flexengage.com/receipts-api.html): Human-facing RapiDoc viewer (JavaScript-rendered, so fetching it returns an empty shell — read the Markdown or YAML above instead, and share this URL with human collaborators who want to browse the API).

## Webhooks API

Webhooks deliver event notifications from flexEngage to your systems via HTTPS callbacks.

- [Markdown companion](https://docs.flexengage.com/webhooks-api.md): Start here — every endpoint, parameter, and schema as plain Markdown, with ready-to-copy curl/Java/C#/Python request samples.
- [OpenAPI spec (YAML)](https://docs.flexengage.com/webhooks-api.yaml): Canonical machine-readable OpenAPI 3 spec; use for exact schemas and codegen.
- [Interactive docs](https://docs.flexengage.com/webhooks-api.html): Human-facing RapiDoc viewer (JavaScript-rendered, so fetching it returns an empty shell — read the Markdown or YAML above instead, and share this URL with human collaborators who want to browse the API).

## Email Validation API

The Email Validation API validates one or many email addresses in real time (frontend pre-transaction or backend post-transaction).

- [Markdown companion](https://docs.flexengage.com/email-validation-api.md): Start here — every endpoint, parameter, and schema as plain Markdown, with ready-to-copy curl/Java/C#/Python request samples.
- [OpenAPI spec (YAML)](https://docs.flexengage.com/email-validation-api.yaml): Canonical machine-readable OpenAPI 3 spec; use for exact schemas and codegen.
- [Interactive docs](https://docs.flexengage.com/email-validation-api.html): Human-facing RapiDoc viewer (JavaScript-rendered, so fetching it returns an empty shell — read the Markdown or YAML above instead, and share this URL with human collaborators who want to browse the API).

## Optional

- [Webhooks integration guide](https://docs.flexengage.com/webhooks/webhooks-integration-guide.md): How to subscribe to events and consume notifications.
- [Webhooks signature verification](https://docs.flexengage.com/webhooks/signature-verification.md): How to verify the authenticity of incoming webhook payloads.
- [Webhooks supported event types](https://docs.flexengage.com/webhooks/supported-event-types.md): Reference list of event types flexEngage publishes.
- [Receipts integration guide](https://docs.flexengage.com/receipts/receipts-integration-guide.md): How to integrate a POS system with the Receipts API — authentication, request/response handling, error handling, and best practices.
- [Receipts request field reference](https://docs.flexengage.com/receipts/request-reference.md): Field-by-field usage notes for headers, discounts, loyalty, tenders, taxes, items, and custom fields.
- [Receipts data elements](https://docs.flexengage.com/receipts/receipt-data-elements.md): How request fields map to sections of a rendered receipt — orders, returns, totals, deposits, and payment history.
- [Receipts POS UI guidelines](https://docs.flexengage.com/receipts/pos-ui-guidelines.md): Recommended configuration options and UI flow for the receipt-selection experience.
- [Receipts printed offers](https://docs.flexengage.com/receipts/printed-offers.md): How printed offers are requested, returned, and configured (package-dependent feature).
- [Receipts SMS receipts](https://docs.flexengage.com/receipts/sms-receipts.md): How to send receipts via SMS instead of email (package-dependent feature).
- [Receipts integration testing checklist](https://docs.flexengage.com/receipts/testing-checklist.md): Checklist for validating a Receipts API integration before launch.
- [Full concatenated docs](https://docs.flexengage.com/llms-full.txt): All three API Markdown companions in a single file.