> ## 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.
# Introduction
> Build on the world's product graph with the Closient API.
Closient is a product data platform that connects brands, retailers, and developers to structured product information through GTINs (Global Trade Item Numbers). The platform combines product catalog management, GS1 Digital Link resolution, supply chain event tracking (EPCIS 2.0), and proximity-based local search into a unified API.
## Who Is This For
* **Brands** managing product data, resolver rules, and supply chain visibility
* **Retailers** connecting POS systems and managing local inventory
* **Developers** integrating product lookup, barcode scanning, or Digital Link resolution
## Core Capabilities
GTIN-based product records with images, certifications, dimensions, GPC classification, and data provenance tracking. Products are identified by GTIN-14 (zero-padded from GTIN-8/12/13).
Resolve any GTIN to structured product data via GS1-conformant URIs. Supports Application Identifiers for batch/lot (AI 10), serial (AI 21), expiry (AI 17), and more. Configurable resolution rules with time-based routing and scope hierarchy.
Capture and query supply chain visibility events per ISO/IEC 19987:2024. Five event types (Object, Aggregation, Transaction, Transformation, Association) with full CBV 2.0 vocabulary support.
Hybrid search combining semantic embeddings, lexical matching, and geographic proximity ranking. Results ranked by distance with relevance gating — closest first, not most relevant first.
## API Design
All APIs share these conventions:
| Convention | Details |
| -------------- | ------------------------------------------------------------------------- |
| Base URL | `https://www.closient.com` |
| Authentication | `X-API-Key` header with format `__` |
| Rate limits | 300/min, 10,000/day per key (custom limits available) |
| Pagination | `?page=1&page_size=25` envelope with `data` + `pagination` |
| Errors | Standard `{ "error": { "code", "message", "status", "details" } }` |
| IDs | Public-facing IDs use nanoid (12 chars, alphabet: `aceghjkpqrtwxy346789`) |
Each API domain (Products, Brands, Locations, etc.) has its own OpenAPI specification and interactive playground in the [API Reference](/api-reference/overview).
## For Users
If you're managing products, brands, or integrations through the Dashboard:
Add, edit, and organize your product catalog.
Establish brand ownership and data authority.
Control where your barcodes direct consumers.
## For Developers
Sign up at [closient.com/accounts/signup](https://www.closient.com/accounts/signup/).
Go to **Settings > API Keys** in your [Dashboard](https://www.closient.com/dashboard/).
See the [Quickstart](/quickstart) for a working example.
## For AI Agents
If you're integrating an AI assistant (Claude, Cursor, Claude Desktop,
VS Code, Windsurf, or a custom MCP client) with Closient, start with
[How AI Agents Use Closient](/prompts/mcp-for-ai-agents) — answers to
the questions developers actually ask AI assistants about product data
and barcode lookup. See also the [Developer Questions](/prompts/index)
index for prompt-mapped landing pages.