openapi: 3.2.0
info:
  title: ATF eRegulations Search API
  version: '2026-09-05'
  summary: Read-only JSON API over ATF's eRegulations platform (27 CFR Parts 447, 478, 479, 555, 646, 771).
  description: Machine-readable description of the public JSON API served at https://regulations.atf.gov/api/.
  contact:
    name: Bureau of Alcohol, Tobacco, Firearms and Explosives
    url: https://www.atf.gov/contact
  license:
    name: U.S. Government Work (17 U.S.C. 105)
    url: https://www.usa.gov/government-works
servers:
- url: https://regulations.atf.gov/api
  description: ATF eRegulations production API (anonymous, no key)
tags:
- name: Search
  description: Full-text search across regulation text.
paths:
  /search:
    get:
      operationId: searchRegulationText
      tags:
      - Search
      summary: Full-text search across regulation text
      parameters:
      - name: q
        in: query
        required: true
        description: Search terms. Required — omitting it returns HTTP 400.
        schema:
          type: string
          examples:
          - firearm
      - name: regulation
        in: query
        required: false
        description: Restrict results to one CFR part.
        schema:
          type: string
          examples:
          - '478'
      - name: version
        in: query
        required: false
        description: Restrict results to one effective version.
        schema:
          type: string
          examples:
          - 2026-01141
      - name: page
        in: query
        required: false
        description: Zero-based page of results.
        schema:
          type: integer
          minimum: 0
          examples:
          - 1
      responses:
        '200':
          description: Search results
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SearchResults'
        '400':
          description: Missing or invalid query parameter
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidationError'
components:
  schemas:
    SearchHit:
      type: object
      properties:
        text:
          type: string
        label:
          type: array
          items:
            type: string
        label_string:
          type: string
          examples:
          - 478-113a
        version:
          type: string
        regulation:
          type: string
        match_title:
          type: string
        paragraph_title:
          type: string
        section_title:
          type: string
        title:
          type: string
    ValidationError:
      type: object
      required:
      - reason
      properties:
        reason:
          type: object
          description: Field name -> list of validation messages.
          additionalProperties:
            type: array
            items:
              type: string
      examples:
      - reason:
          q:
          - Missing data for required field.
    SearchResults:
      type: object
      required:
      - total_hits
      - results
      properties:
        total_hits:
          type: integer
          examples:
          - 1596
        results:
          type: array
          items:
            $ref: '#/components/schemas/SearchHit'
x-generated-from: live probe of https://regulations.atf.gov/api/* on 2026-09-05
x-api-evangelist-modeled: true
x-upstream-project: https://github.com/atfweb/regulations-core