> ## Documentation Index
> Fetch the complete documentation index at: https://developers.telnyx.com/llms.txt
> Use this file to discover all available pages before exploring further.

# APIs fundamentals llms.txt

> Machine-readable documentation index for APIs fundamentals (Development) — guide pages and API endpoints for AI agents and LLMs

# Telnyx Development: APIs fundamentals — Documentation Index

> APIs fundamentals documentation within the Development section of the Telnyx developer docs ([https://developers.telnyx.com](https://developers.telnyx.com)).
> Root index: [https://developers.telnyx.com/llms.txt](https://developers.telnyx.com/llms.txt) · Development index: [https://developers.telnyx.com/development/llms-txt.md](https://developers.telnyx.com/development/llms-txt.md) · Full content for this subsection: [https://developers.telnyx.com/development/llms/development-apis-fundamentals-llms-full-txt.md](https://developers.telnyx.com/development/llms/development-apis-fundamentals-llms-full-txt.md)

* [Create API Keys](https://developers.telnyx.com/development/api-fundamentals/create-api-keys.md): Step-by-step guide to create, manage, and secure your Telnyx API keys for all services.

## Authentication & Security

* [API Authentication](https://developers.telnyx.com/development/api-fundamentals/authentication.md): Authentication methods and security best practices for all Telnyx APIs.

## Request & Response

* [HTTP Patterns](https://developers.telnyx.com/development/api-fundamentals/request-response.md): Universal patterns for making requests and handling responses across all Telnyx APIs.

## Error Reference

* [API error codes](https://developers.telnyx.com/development/api-fundamentals/api-errors.md): Comprehensive reference of all Telnyx API error codes with descriptions and solutions.

## Reliability & Performance

* [Rate Limiting](https://developers.telnyx.com/development/api-fundamentals/reliability/rate-limiting.md): Understand rate limits on the Telnyx REST API, including limit headers, retry strategies, and best practices for handling 429 responses across all services.
* [API Reliability & Retries](https://developers.telnyx.com/development/api-fundamentals/reliability/command-retries.md): Best practices for handling API errors, implementing retries, and building resilient integrations across all Telnyx services.

## Webhooks & Events

* [Webhook Fundamentals](https://developers.telnyx.com/development/api-fundamentals/webhooks/receiving-webhooks.md): Receive, handle, and secure webhooks from Telnyx APIs. Covers webhook setup, signature verification, payload structure, and retries for Voice, SMS, and Fax.

## Data Standards

* [Parameters & Field Names](https://developers.telnyx.com/development/api-fundamentals/data-standards/parameters-fields.md): Comprehensive guide to Telnyx API parameter and field naming conventions, data types, and formatting standards.