# Zeno

> Device identification and fraud signals for websites. A browser agent identifies each visitor (one browser on one device, `visitorId`) and stores an event (`requestId`); your server reads the event with a secret key and decides on its detected signals, risk score, bot verdict, velocity and related IDs.

The browser agent loads from https://zenocdn.net/agent.js and identifies there (its `endpoint`, or the project's custom domain). The server API is at https://api.zeno.id, without a version prefix, authenticated with a secret key in the `Auth-API-Key` header. Requests with a body need an `x-amz-content-sha256` header with the hex SHA-256 of the body. Every page below is server rendered HTML, with the code of every tab (fetch, Node SDK, Python, PHP, Go and the frameworks) in it; the tabs a browser hides are hidden `role="tabpanel"` elements named by `data-label`.

## Get started

- [Overview](https://zeno.id/docs): what the service does, with a first code sample.
- [Key terms](https://zeno.id/docs/key-terms): Visitor, event, external ID, project, capped and the other words these docs use, each in one sense.
- [Quickstart](https://zeno.id/docs/quickstart): Identify your first visitor with the hosted script, serve the agent from your custom domain for production, and verify the event on your server.

## Browser

- [Browser agent](https://zeno.id/docs/agent): Install and start the agent, identify visitors, and handle errors, single page apps and local development.
- [Custom domain](https://zeno.id/docs/custom-domain): Serve the agent from a subdomain of your site with one DNS record, so blocklists aimed at third-party domains miss it: setup, naming, status, Safari cookies and CSP.

## Server

- [Server API](https://zeno.id/docs/server-api): Authenticate with a secret key, send bodies with their hash, handle errors and the rate limit, from any language.
- [Events](https://zeno.id/docs/events): Read one event with all its details, and attach an external ID to it afterwards.
- [Smart signals](https://zeno.id/docs/smart-signals): What each flag means and how sure it is, how the risk score adds up, and what to do with it.
- [Search events](https://zeno.id/docs/search): Filter your project's events by visitor, external ID, IP, signal, score and date, and page through them.
- [Visitors and external IDs](https://zeno.id/docs/visitors): Look up a visitor with every external ID seen with it, and erase visitors or external IDs.
- [Related](https://zeno.id/docs/related): Link your external IDs to the visitors and IPs they were seen with, find duplicates and the external IDs related to one.
- [Webhooks](https://zeno.id/docs/webhooks): Get every new event POSTed to your server, signed.
- [Sealed results](https://zeno.id/docs/sealed-results): Trust the event the browser hands you without calling the API.
- [Server SDK](https://zeno.id/docs/server-sdk): A typed Node client that handles the body hash, retries, webhooks and sealed results, and what to do without it.
- [AI assistants](https://zeno.id/docs/ai-assistants): llms.txt, Copy for LLM, and an MCP server that gives an assistant your project's server API.

## Manage

- [Keys and billing](https://zeno.id/docs/keys-and-billing): Public and secret keys, allowed origins, the beta usage limit, how you're billed, budgets and the key format.
- [Project settings](https://zeno.id/docs/project-settings): Zero trust mode, data retention, page URLs, risk score weights, support access and the project's secrets.
- [Privacy and consent](https://zeno.id/docs/privacy-and-consent): What the agent reads and stores, starting it only after consent or where you need it, keeping and erasing less, and your privacy policy.
- [Dashboard](https://zeno.id/docs/dashboard): Every page of the dashboard, and how to review a suspicious signup without writing code.
- [Support](https://zeno.id/docs/support): Get help through a ticket in the dashboard: statuses, priority support for paying organizations, and support access.

## Security and legal

- [Security](https://zeno.id/security): how the service is run and what it stores, where.
- [Legal](https://zeno.id/legal): every policy.
- [Acceptable Use Policy](https://zeno.id/legal/acceptable-use): What Zeno may and may not be used for.
- [Privacy Policy](https://zeno.id/legal/privacy): What Zeno collects, why, how long it keeps it and the choices you have.
- [Sub-processors](https://zeno.id/legal/sub-processors): The providers that process personal data for Zeno, where, and how we announce changes.
- [Recruitment Privacy Notice](https://zeno.id/legal/recruitment-privacy): How we handle your data when you apply for a job with us.
- [Europe Privacy Policy Addendum](https://zeno.id/legal/europe-privacy): Additional information for people in the EEA, the United Kingdom and Switzerland.
- [Satisfaction Guarantee](https://zeno.id/legal/satisfaction-guarantee): Not satisfied in your first three months of paid use? Everything you paid back, no questions asked.
- [Cookie Policy](https://zeno.id/legal/cookies): The cookies and browser storage Zeno and its website use.