---
title: "API Reference"
description: "Exact configuration, collection, field, and Client SDK contracts, with links to the subsystem references that own search, authentication, uploads, rich text, routing, and storage."
canonical: "https://bylinecms.app/docs/api-reference"
locale: "en"
collection: "docs"
updated: "2026-07-31T14:47:54.239Z"
---

# API Reference

Exact configuration, collection, field, and Client SDK contracts, with links to the subsystem references that own search, authentication, uploads, rich text, routing, and storage.

Companions:

- [Configuration](/docs/getting-started/configuration) — an introductory tour of the application files and runtime boundaries behind these contracts.
- [Key architectural decisions](/docs/architecture) — the design context for the APIs listed here.
- [Testing](/docs/testing) — the unit, integration, and browser suites used to verify these contracts.

This section is the lookup surface for Byline's application-facing APIs. Use it when you know which system you are configuring and need the exact properties, defaults, parameters, return shapes, or runtime restrictions.

## Core references

- [Configuration API](/docs/api-reference/configuration-reference) documents `BaseConfig`, `ClientConfig`, `ServerConfig`, `BylineCore`, configuration registration, and server client getters.
- [Collections API](/docs/api-reference/collections-reference) documents `CollectionDefinition`, `CollectionAdminConfig`, `BlockAdminConfig`, workflow configuration, and lifecycle hooks.
- [Fields API](/docs/api-reference/field-reference) documents the common field contract, all 22 built-in field kinds, default values, validation, hooks, and admin field overrides.
- [Client SDK API](/docs/api-reference/client-sdk-reference) documents `BylineClientConfig`, `BylineClient`, every public `CollectionHandle` method, shared read and write options, and result envelopes.

## Subsystem references

These existing documents remain the canonical references for their narrower contracts:

| Surface | Canonical reference |
| --- | --- |
| Authentication, actors, abilities, and sessions | [Authentication and authorization](/docs/auth-and-security/authn-authz) |
| Audit log and version attribution | [Auditability](/docs/auth-and-security/audit) |
| File and image uploads, `UploadConfig`, and upload hooks | [File and media uploads](/docs/collections/file-media-uploads) |
| Relation fields, populate, and relation envelopes | [Relationships](/docs/collections/relationships) |
| Rich-text editor and server adapters | [Rich text](/docs/collections/richtext) |
| Document paths and slugifiers | [Document paths](/docs/collections/document-paths) |
| Document trees | [Document trees](/docs/collections/document-tree) |
| Search collection configuration | [Search configuration](/docs/search/configure-search) |
| Search query API | [Search API](/docs/search/search-api) |
| `SearchProvider` implementation contract | [Search provider contract](/docs/search/search-provider-contract) |
| Admin and API route mounts | [Routing and API](/docs/reading-and-delivery/routing-api) |
| Interface and content locale configuration | [Internationalization](/docs/i18n) |
| Database adapter contract and boot composition | [Core composition](/docs/architecture/core-composition) |
| Typed EAV storage and stored value shapes | [Document storage](/docs/architecture/core-document-storage) |

## Reference conventions

- A property without `?` is required by TypeScript.
- “Conditional” means the property is optional in the type but required when another configured feature uses it.
- Defaults describe current runtime behavior when the property is omitted.
- `_`-prefixed options are internal or trusted-tooling escape hatches, even when TypeScript exposes them for hook re-entry.
- The implementation and exported TypeScript types remain authoritative when a reference and a locally installed package version differ.