# Backlit

> Reference documentation for the Backlit SDK and protocol.

## Docs

- [Introduction](https://usebacklit.com/docs/introduction): What Backlit is, the work it removes, and the packages it ships.
- [Server-driven UI](https://usebacklit.com/docs/sdui): The background of server-driven UI, how it works in Backlit, and where it fits.
- [Key concepts](https://usebacklit.com/docs/concepts): The terms that the Backlit SDK and the reference use, and how they relate.
- [Getting started](https://usebacklit.com/docs/getting-started): Add Backlit to an existing app or create a new app with a coding agent.
- [Extensions](https://usebacklit.com/docs/extensions): Install finished screens, new fields, and new blocks as packages.
- [The Backlit manifesto](https://usebacklit.com/docs/manifesto): The operating system for your back office.

## Reference

- [App and areas](https://usebacklit.com/docs/reference/app): Register resources, navigation, and request handlers.
- [Resources](https://usebacklit.com/docs/reference/resources): Declare a named entity, its fields, and its Backlit endpoints.
- [Request handling](https://usebacklit.com/docs/reference/requests): Use request context, middleware, transport, and responses.
- [Search state](https://usebacklit.com/docs/reference/state): Register filters, sorting, and pagination on views and zones.
- [Agent tools](https://usebacklit.com/docs/reference/agents): Describe selected views and actions for agent clients.

### Fields

- [Fields](https://usebacklit.com/docs/reference/fields): Describe the data type, the format, and the rendering of each piece of data in your app.
- [Text field](https://usebacklit.com/docs/reference/fields/text): Display a string as plain text or a common contact value.
- [Number field](https://usebacklit.com/docs/reference/fields/number): Display a number as a count, a decimal, a currency amount, a percentage, or a progress against a total.
- [Boolean field](https://usebacklit.com/docs/reference/fields/boolean): Display a true or false value.
- [Date field](https://usebacklit.com/docs/reference/fields/date): Display an instant as a date, time, date-time, or relative value.
- [Enum field](https://usebacklit.com/docs/reference/fields/enum): Display one or more values from a declared option set.
- [Group field](https://usebacklit.com/docs/reference/fields/group): Display multiple record keys as one composite value.
- [Ref field](https://usebacklit.com/docs/reference/fields/ref): Display records that the current record points to.
- [Has field](https://usebacklit.com/docs/reference/fields/has): Display records that point back to the current record.

### Filters

- [Filters](https://usebacklit.com/docs/reference/filters): Declare the controls that narrow the data of a view or a zone.
- [Text filter](https://usebacklit.com/docs/reference/filters/text): Filter data with free text.
- [Toggle filter](https://usebacklit.com/docs/reference/filters/toggle): Filter data with a three-state choice.
- [Select filter](https://usebacklit.com/docs/reference/filters/select): Filter data with one or more declared choices.
- [Date-range filter](https://usebacklit.com/docs/reference/filters/date-range): Filter data between two calendar dates.
- [Number-range filter](https://usebacklit.com/docs/reference/filters/number-range): Filter between two numbers on a declared scale.
- [Period filter](https://usebacklit.com/docs/reference/filters/period): Select a calendar unit for grouped data.
- [Filter binding and placement](https://usebacklit.com/docs/reference/filters/binding): Bind, read, and display filters in a view or zone.

### Views, zones, actions, and lookups

- [Views, zones, actions, and lookups](https://usebacklit.com/docs/reference/views): The endpoints of a resource, which read data, change data, and supply options.
- [View](https://usebacklit.com/docs/reference/views/view): Register and build one addressable Backlit screen.
- [Zone](https://usebacklit.com/docs/reference/views/zone): Define part of a view that can refresh on its own.
- [Action](https://usebacklit.com/docs/reference/views/action): Validate an operation and return its next interface state.
- [Lookup definition](https://usebacklit.com/docs/reference/views/lookup): Return fields and records for search and options inputs.

### Blocks

- [Blocks](https://usebacklit.com/docs/reference/blocks): Compose the content and the layout of a screen from blocks.
- [Table](https://usebacklit.com/docs/reference/blocks/table): Display multiple records in declared columns.
- [List](https://usebacklit.com/docs/reference/blocks/list): Display records with shared fields or configure each item.
- [Timeline](https://usebacklit.com/docs/reference/blocks/timeline): Display events with shared fields or configure each event.
- [Callout](https://usebacklit.com/docs/reference/blocks/callout): Display a short message near the content that it describes.
- [Panel](https://usebacklit.com/docs/reference/blocks/panel): Group related content inside one bounded surface.
- [Section](https://usebacklit.com/docs/reference/blocks/section): Organize a page into named or unnamed regions.
- [Tabs](https://usebacklit.com/docs/reference/blocks/tabs): Switch between bands of content that a reader takes one at a time.
- [Datalist](https://usebacklit.com/docs/reference/blocks/datalist): Display one record as a list of labeled values.
- [Group](https://usebacklit.com/docs/reference/blocks/group): Keep related blocks in one content group.
- [Segments](https://usebacklit.com/docs/reference/blocks/segments): Show one select filter as a row of buttons.

### Forms

- [Forms](https://usebacklit.com/docs/reference/forms): Collect values from a user and submit them to an action.
- [Form](https://usebacklit.com/docs/reference/forms/form): Display fields that submit data to a Backlit action.
- [Form fields](https://usebacklit.com/docs/reference/forms/form-fields): Add ordered fields to a form and place related fields on one line.
- [Form conditions](https://usebacklit.com/docs/reference/forms/conditions): Show and enable fields from typed form values.
- [Form repeater](https://usebacklit.com/docs/reference/forms/repeater): Edit an array of records in one form.

### Widgets

- [Widgets and charts](https://usebacklit.com/docs/reference/widgets): Show figures and charts that summarize data, for dashboards and overview pages.
- [Widget](https://usebacklit.com/docs/reference/widgets/widget): Display a figure, a chart, or both, with the context that reads them.
- [Widget group](https://usebacklit.com/docs/reference/widgets/group): Display related widgets as one set.
- [Charts](https://usebacklit.com/docs/reference/widgets/charts): Build bar lists, lines, spark areas, and category bars.

### Targets

- [Targets](https://usebacklit.com/docs/reference/targets): Connect fields, rows, buttons, and inputs to views, actions, and lookups.
- [Link target](https://usebacklit.com/docs/reference/targets/link): Display a related value as a link to another Backlit view.
- [Visit target](https://usebacklit.com/docs/reference/targets/visit): Define a standalone control that opens another Backlit view.
- [Action target](https://usebacklit.com/docs/reference/targets/action): Submit a small action directly or through a dialog.
- [Lookup target](https://usebacklit.com/docs/reference/targets/lookup): Let a form input select a value from fetched records.

### API declarations

- [API declarations](https://usebacklit.com/docs/reference/api): Read every public SDK export.

- [SDK API](https://usebacklit.com/docs/reference/api/sdk): Complete public declarations from @backlit/sdk.
- [SDK types](https://usebacklit.com/docs/reference/api/types): Complete public declarations from @backlit/sdk/types.
- [SDK symbols](https://usebacklit.com/docs/reference/api/symbols): Complete public declarations from @backlit/sdk/symbols.

## Advanced

- [SDK extensions](https://usebacklit.com/docs/advanced/extensions): Add server behavior and keep field conversion explicit.
- [Extend field roles](https://usebacklit.com/docs/advanced/field-roles): Convert and display a field value through a custom role.

## Other

- [Backlit reference](https://usebacklit.com/docs): Define internal application interfaces with the Backlit SDK and render them from the Backlit protocol.

## Agent resources

- [llms-full.txt](https://usebacklit.com/llms-full.txt): The full Markdown of every page in one file.
- [Page Markdown](https://usebacklit.com/index.md): Append `.md` to any page URL to fetch that page as raw Markdown.
- [JSON API](https://usebacklit.com/api/docs/pages.json): Page index of the JSON docs API; each entry links the page's JSON and Markdown forms. Described by the OpenAPI document at https://usebacklit.com/openapi.json.
- [API catalog](https://usebacklit.com/.well-known/api-catalog): RFC 9727 linkset of the APIs documented here.
- [agent-readability.json](https://usebacklit.com/agent-readability.json): Manifest of every agent-facing artifact on this site.
- [Sitemap](https://usebacklit.com/sitemap.xml): Every indexable page URL with its last-modified date.