> ## Documentation Index > Fetch the complete documentation index at: https://docs.closient.com/llms.txt > Use this file to discover all available pages before exploring further. # Compress Application Identifiers into a GS1 Digital Link path segment > Bit-pack a primary key plus optional qualifiers/attributes into the single opaque base64url path segment defined by GS1's Digital Link compression scheme — the exact inverse of `/decompress`. Takes the same `primary_ai` / `primary_value` / repeated `qualifier=code:value` / `attribute=code:value` shape as `/build`, so the same query string composes both the uncompressed and compressed forms of an identifier set. An AI set that cannot be compressed (unknown AI code, malformed value, no primary identifier) is a `200` with `is_valid: false` and the reason — the same triage contract as `/validate` and `/decompress`. **Keyless** — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a `429` with a `Retry-After` header and a `retry_after` field — it never silently degrades or returns a wrong answer under load. ## OpenAPI ````yaml /openapi/openapi-resolver.json get /resolver/api/v1/public/gs1/compress openapi: 3.1.0 info: title: Resolver API version: 1.0.0 description: > GS1 Digital Link resolution with content negotiation and linkset support. ## Authentication All endpoints require an API key passed via the `X-API-Key` HTTP header, unless otherwise noted. ``` X-API-Key: csb__ ``` Generate API keys in **Settings > API Keys** in your dashboard, or via the Account API. Session-based (cookie) authentication is also accepted for browser-based access. ## Rate Limits | Tier | Requests / minute | Requests / day | |-------------|-------------------|----------------| | Default | 300 | 10,000 | | Custom | Contact us | Contact us | Rate-limit headers are included on every response so callers can self-throttle without hitting our 429s ("informed governor"): - `RateLimit-Policy` — every active window, e.g. `300;w=60, 10000;w=86400` - `RateLimit-Limit` — quota for the **most-restrictive** currently-active window - `RateLimit-Remaining` — requests left in that window - `RateLimit-Reset` — seconds until that window resets (relative; clock-skew safe) Legacy `X-RateLimit-*` aliases are also emitted for back-compat. `X-RateLimit-Reset` keeps the absolute Unix-timestamp shape to avoid breaking existing consumers. When rate-limited, you receive `429 Too Many Requests` with a `retry_after_seconds` field in the error envelope and a `Retry-After` header. ## Pagination List endpoints return paginated results in this envelope: ```json { "data": [...], "pagination": { "page": 1, "page_size": 25, "total_count": 342, "total_pages": 14, "has_next": true, "has_previous": false } } ``` Use `?page=2&page_size=50` query parameters. Maximum page size is 100. ## Error Responses All errors conform to [RFC 9457 Problem Details](https://www.rfc-editor.org/rfc/rfc9457) with `Content-Type: application/problem+json`: ```json { "type": "https://closient.com/docs/errors/not_found", "title": "Not Found", "status": 404, "detail": "The requested resource was not found.", "error_code": "not_found", "retryable": false, "timestamp": "2026-03-31T12:00:00+00:00" } ``` Common error codes: `unauthorized` (401), `forbidden` (403), `not_found` (404), `validation_error` (422), `rate_limited` (429), `internal_error` (500). termsOfService: https://www.closient.com/terms/ servers: - url: https://www.closient.com security: [] tags: - name: Resolver description: GS1 Digital Link resolution with content negotiation and linkset support. - name: Custom URLs description: >- Reusable custom-URL catalog (C-3339) — create, list, edit, and delete the custom redirect destinations that resolution rules point at. - name: Verification description: >- Serial verification (`gs1:verificationService`) — tiered, rate-limited responses for serialized GTIN scans. Experimental v1; see the verification-service guide. - name: GS1 Primitives (Public) description: >- Keyless GS1 Digital Link primitives (C-4295) — parse, validate, build, decompress, and check-digit analysis. **No API key, no signup.** Pure functions over strings: no database, no network, no catalog data. IP-throttled and edge-cached so repeat calls cost nothing. This is the reference implementation the resolver itself runs on. - name: Resolver Custom Hostnames description: >- BYO domain (C-4058) — register a customer-owned hostname, publish the CNAME records, verify ownership, and serve an org's Digital Link QRs from its own DNS. externalDocs: description: Closient Documentation url: https://docs.closient.com paths: /resolver/api/v1/public/gs1/compress: get: tags: - GS1 Primitives (Public) summary: Compress Application Identifiers into a GS1 Digital Link path segment description: >- Bit-pack a primary key plus optional qualifiers/attributes into the single opaque base64url path segment defined by GS1's Digital Link compression scheme — the exact inverse of `/decompress`. Takes the same `primary_ai` / `primary_value` / repeated `qualifier=code:value` / `attribute=code:value` shape as `/build`, so the same query string composes both the uncompressed and compressed forms of an identifier set. An AI set that cannot be compressed (unknown AI code, malformed value, no primary identifier) is a `200` with `is_valid: false` and the reason — the same triage contract as `/validate` and `/decompress`. **Keyless** — no API key, no signup. IP-throttled at 300 requests/minute and cached at the edge for 24h, so repeat calls for the same input do not reach origin. Over-rate callers get a `429` with a `Retry-After` header and a `retry_after` field — it never silently degrades or returns a wrong answer under load. operationId: apps_resolver_api_public_gs1_compress_digital_link_public parameters: - in: query name: primary_ai schema: description: The primary identifier AI code, e.g. `01` for GTIN. maxLength: 4 minLength: 2 title: Primary Ai type: string required: true description: The primary identifier AI code, e.g. `01` for GTIN. - in: query name: primary_value schema: description: The primary identifier's value, e.g. `09506000164908`. maxLength: 256 minLength: 1 title: Primary Value type: string required: true description: The primary identifier's value, e.g. `09506000164908`. - in: query name: qualifier schema: default: [] description: Repeatable qualifier AI in `code:value` form, e.g. `10:LOT1`. items: type: string title: Qualifier type: array required: false description: Repeatable qualifier AI in `code:value` form, e.g. `10:LOT1`. - in: query name: attribute schema: default: [] description: >- Repeatable data-attribute AI in `code:value` form, e.g. `17:261231`. items: type: string title: Attribute type: array required: false description: Repeatable data-attribute AI in `code:value` form, e.g. `17:261231`. responses: '200': description: OK content: application/json: schema: $ref: '#/components/schemas/DigitalLinkCompressOut' '400': description: Bad Request content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '404': description: Not Found content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '405': description: Method Not Allowed content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '422': description: Unprocessable Content content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' '429': description: Too Many Requests content: application/problem+json: schema: $ref: '#/components/schemas/ErrorOut' components: schemas: DigitalLinkCompressOut: description: A GS1-compressed Digital Link path segment plus how it graded. examples: - ai_map: '01': '09506000164908' compressed_path: /ARFKk4awWA compressed_segment: ARFKk4awWA is_valid: true properties: ai_map: additionalProperties: type: string description: >- The `{ai_code: value}` map that was compressed, echoed back for confirmation. title: Ai Map type: object is_valid: description: True when the AI map compressed successfully. title: Is Valid type: boolean error: anyOf: - type: string - type: 'null' description: Why compression failed, or `null` on success. title: Error compressed_segment: anyOf: - type: string - type: 'null' description: >- The opaque base64url path segment, or `null` when compression failed. examples: - ARFKk4awWA title: Compressed Segment compressed_path: anyOf: - type: string - type: 'null' description: >- The GS1-canonical root-relative compressed path (`/`), as served at `id.gs1.org`, or `null` when compression failed. Closient's own resolver serves compressed Digital Links under a `/c/` prefix instead — see `docs.closient.com` for why. examples: - /ARFKk4awWA title: Compressed Path required: - ai_map - is_valid title: DigitalLinkCompressOut type: object ErrorOut: description: |- RFC 9457 Problem Details response. All API errors are returned in this format with Content-Type: application/problem+json. examples: - detail: The requested resource was not found. error_code: not_found retryable: false status: 404 timestamp: '2026-03-31T12:00:00+00:00' title: Not Found type: https://closient.com/docs/errors/not_found - detail: Validation error. details: - loc: - body - name msg: Field required type: missing error_code: validation_error retryable: false status: 422 timestamp: '2026-03-31T12:00:00+00:00' title: Validation Error type: https://closient.com/docs/errors/validation_error - detail: Rate limit exceeded. Please try again later. error_code: rate_limited retry_after: 31 retryable: true status: 429 timestamp: '2026-03-31T12:00:00+00:00' title: Rate Limited type: https://closient.com/docs/errors/rate_limited properties: type: description: URI reference identifying the error type. title: Type type: string title: description: Short human-readable summary of the error. title: Title type: string status: description: HTTP status code. title: Status type: integer detail: description: Human-readable explanation of this specific occurrence. title: Detail type: string error_code: description: Machine-readable error code (e.g. not_found, unauthorized). title: Error Code type: string retryable: default: false description: Whether retrying the same request can succeed. title: Retryable type: boolean timestamp: description: ISO 8601 timestamp of when the error occurred. title: Timestamp type: string retry_after: anyOf: - type: integer - type: 'null' description: Seconds to wait before retrying (when applicable). title: Retry After owner_action_required: anyOf: - type: boolean - type: 'null' description: Whether the error requires account owner intervention. title: Owner Action Required details: description: Additional context (validation errors, etc.). title: Details required: - type - title - status - detail - error_code - timestamp title: ErrorOut type: object ````