# Stablegate API > Stablegate is a processing infrastructure that lets businesses offer on-ramp (fiat-to-crypto) and off-ramp (crypto-to-fiat) services through a single REST API. It handles customer KYC, compliance, bank settlement (SEPA), blockchain settlement (Ethereum, Tron, Stellar), order lifecycle, and webhooks. Integration essentials: - Base URL: `https://api.stablegate.com`, version prefix `/v1/`. - Authentication: every request sends the `X-Api-Key` header. Keys are issued in the Developers section at `https://app.stablegate.com/developers`. - Idempotency: mutating endpoints accept an `Idempotency-Key` header for safe retries. - Supported rails: `sepa` (EUR bank transfers), `ethereum`, `tron` and `stellar` (on-chain transfers). Always lowercase. - Supported assets: `EUR`; `USDT` on `ethereum` or `tron`; `USDC` on `ethereum` or `stellar`; `EURC` on `ethereum`. Always uppercase. - Country codes: ISO 3166-1 **alpha-3** (e.g. `CHE`, `LTU`, `GBR`). Never alpha-2. - Order statuses: `new`, `processing`, `done`, `hold`, `failed`, `rejected`, `rollbacked`, `cancelled`. - Webhooks: HMAC-signed HTTP POST callbacks for order and customer events. - Typical integration sequence: create customer → register external accounts → check route → check fees and limits → create order → observe via webhook or poll. ## Getting Started - [Introduction](https://docs.stablegate.com/docs/guide): platform overview, key concepts, supported exchange routes, base URL, API version. - [Getting Started](https://docs.stablegate.com/docs/guide/getting-started): Developers section access, API key creation, first `curl` call, integration flow diagram. - [Coverage](https://docs.stablegate.com/docs/guide/getting-started/coverage): supported routes, customer types, verification paths, account types and events, and what is done through the API versus by Stablegate on request. - [Quickstart](https://docs.stablegate.com/docs/guide/getting-started/quickstart): seven requests from an API key to a paid-out on-ramp order, with the timings to expect. - [Authentication](https://docs.stablegate.com/docs/guide/getting-started/authentication): `X-Api-Key` header usage, key rotation guidance. - [Idempotency](https://docs.stablegate.com/docs/guide/getting-started/idempotency): `Idempotency-Key` header semantics, replay behaviour, recommended key generation. - [Postman Collection](https://docs.stablegate.com/docs/guide/getting-started/postman-collection): pre-built Postman collection with all endpoints and environment variables. - [For LLM Agents](https://docs.stablegate.com/docs/guide/getting-started/llm-agents): overview of the machine-readable resources (`llms.txt`, `llms-full.txt`, `openapi.json`) and when to use each. - [Errors](https://docs.stablegate.com/docs/guide/getting-started/errors): the body of every failed request, the status codes, the `devapi_*` codes with what to do about each, `oa_*` and `ca_*` from internal services, and the retry rules. ## Core Resources - [Customers](https://docs.stablegate.com/docs/guide/customers): create, fetch, list, update customer records; customer UUID scoping rules. - [External Accounts](https://docs.stablegate.com/docs/guide/external-accounts): register and list IBAN bank accounts and crypto wallets for a customer. - [Exchange Routes](https://docs.stablegate.com/docs/guide/exchange-routes): discover supported source/destination pairs (rail + asset). - [Bank Providers](https://docs.stablegate.com/docs/guide/bank-providers): list banks, the rails they support, and the routes accessible through each bank. - [Fees and Limits Overview](https://docs.stablegate.com/docs/guide/fees-and-limits): how fees and limits interact in a transaction flow. - [Fees](https://docs.stablegate.com/docs/guide/fees-and-limits/fees): request a fee quote including exchange rate before placing an order. - [Limits](https://docs.stablegate.com/docs/guide/fees-and-limits/limits): check a customer's per-transaction and aggregate limits. ## Orders and Webhooks - [Orders](https://docs.stablegate.com/docs/guide/orders): create an order, fetch status, list orders, full status lifecycle (`new` -> `processing` -> `done`/`failed`/...). - [Webhooks](https://docs.stablegate.com/docs/guide/webhooks): register endpoint, event types, payload schemas, HMAC signature verification. ## Integration Workflows - [Integration Guides Index](https://docs.stablegate.com/docs/guide/integration-guides): entry point for flow-level walkthroughs. - [Integration Checklist](https://docs.stablegate.com/docs/guide/integration-guides/checklist): the path from API access to go-live in four phases, with typical integrator mistakes and how to avoid them. - [On-Ramp Walkthrough](https://docs.stablegate.com/docs/guide/integration-guides/onramp): EUR via SEPA to USDC/USDT/EURC on Ethereum, step by step. - [Off-Ramp Walkthrough](https://docs.stablegate.com/docs/guide/integration-guides/offramp): USDC/USDT/EURC on Ethereum to EUR via SEPA, step by step. ## Compliance and Verification - [Verification Common](https://docs.stablegate.com/docs/verification/common): shared rules across individual and business flows. - [Business Profiles](https://docs.stablegate.com/docs/verification/common/business): accepted business forms and classification. - [Non-Serviced Countries](https://docs.stablegate.com/docs/verification/common/countries): jurisdictions that cannot be onboarded (sanctions and internal policy). - [Accepted Documents](https://docs.stablegate.com/docs/verification/common/documents): ID document types per country. - [Terms and Glossary](https://docs.stablegate.com/docs/verification/common/terms): compliance terminology used across the API and docs. - [Individual Compliance](https://docs.stablegate.com/docs/verification/compliance/individual): onboarding flow for natural persons. - [Individual - Verification](https://docs.stablegate.com/docs/verification/compliance/individual/verification): KYC step for individuals. - [Individual - Source of Funds](https://docs.stablegate.com/docs/verification/compliance/individual/sof): SoF requirements for individuals. - [Individual - Activation](https://docs.stablegate.com/docs/verification/compliance/individual/activation): final activation step for individuals. - [Business Compliance](https://docs.stablegate.com/docs/verification/compliance/business): onboarding flow for legal entities. - [Business - Verification](https://docs.stablegate.com/docs/verification/compliance/business/verification): KYB step. - [Business - Source of Funds](https://docs.stablegate.com/docs/verification/compliance/business/sof): SoF requirements for businesses. - [Business - Activation](https://docs.stablegate.com/docs/verification/compliance/business/activation): final activation step for businesses. ## API Reference - [API Reference](https://docs.stablegate.com/docs/apiref): one page per endpoint of the OpenAPI 3.1 spec, with parameters, request body, response schema, error shape and code samples. - [OpenAPI Spec (JSON)](https://docs.stablegate.com/openapi.json): machine-readable OpenAPI 3.1 document. Use this for code generation. - [Authorization Details](https://docs.stablegate.com/docs/apiref/auth): header format and authorization semantics. ## Optional - [Changelog](https://docs.stablegate.com/docs/changelog): dated list of API and documentation changes. - [Full Documentation Bundle](https://docs.stablegate.com/llms-full.txt): every guide, verification page, and a compact endpoint summary concatenated into a single file for direct ingestion.