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

# API overview

> The REST resources for building, evaluating, and backtesting rules-based equity Tilts.

<Warning>
  This is a design preview. The endpoints in this section are not available.
  The reference exists to review the proposed contract before implementation.
</Warning>

The API exposes the same rules-based equity construction model used by Tilt
today, with a deliberately small public surface.

## Core model

A Tilt is a persistent project for one index methodology. Its construction
rules describe how to select and weight securities, and each successful
evaluation saves the constituents and weights those rules produced.

For developers, a bounded analogy is a GitHub repository: construction rules
are source, evaluated constituent snapshots are build artifacts, and
methodology history is version history. The analogy does not imply branches,
forks, merges, or cloning. Evaluating a Tilt does not publish an index.

The existing `version_group_sqid` identifies the project across versions. A
`uuid` addresses one particular draft or published version.

## Workflow

1. Search the construction catalog for exact field names and inspect fields
   before choosing thresholds.
2. List universe presets and create an unevaluated draft Tilt.
3. Resolve ticker overrides to exact `tilt_asset_id` values.
4. Apply the methodology. Tilt saves the rules, evaluates them, and commits the
   complete weighted constituent snapshot atomically.
5. Read the saved constituents or backtest the saved Tilt.

Applying construction is the evaluation operation. A separate evaluation
endpoint, raw catalog listing, and named-index membership endpoint are outside
the initial API scope.

## Scope

The preview includes the documented rules-based equity pipeline: universe,
derived fields, selection, sizing, ticker overrides, rebalance cadence,
concentration limits, complete weighted constituents, and synchronous
backtesting.

It excludes natural-language construction, research, enrichment creation,
discretionary and event-contract Tilts, publication, and governance.

<CardGroup cols={2}>
  <Card title="Build and backtest a Tilt" icon="route" href="/index-construction/api-guide">
    Follow the complete API workflow with requests and responses.
  </Card>

  <Card title="Create a Tilt" icon="plus" href="/api-reference/index-construction-preview/create-tilt">
    Create an unevaluated rules-based equity draft.
  </Card>

  <Card title="Apply construction" icon="code" href="/api-reference/index-construction-preview/apply-construction">
    Save and evaluate the construction methodology.
  </Card>

  <Card title="Get constituents" icon="list" href="/api-reference/index-construction-preview/get-constituents">
    Read the complete saved result with scores and weights.
  </Card>

  <Card title="Search the catalog" icon="magnifying-glass" href="/api-reference/index-construction-preview/search-catalog">
    Discover fields and supported expression functions.
  </Card>
</CardGroup>