Developers

Reference data and pagination

The rail, asset and country catalogues are the same source that feeds the site. They carry limits, delays, fees and field schemas — enough to generate your payout form instead of coding it country by country.

Refresh frequency

This data changes rarely, but it does change: a rail cap, a cut-off, a country opening. Refresh it at least daily, and do not freeze it into your code. Each entry carries a last manual verification date: past six months, treat it as due for a check.

Pagination

Cursor pagination, not numeric offsets. An offset skips or duplicates items as soon as the list moves between two pages; a cursor points at a stable position.

Requesthttp

GET /api/v1/rails?limit=50&cursor=cJ0xNzg4MzU2OTgx

Responsejson

{
  "data": [ /* … */ ],
  "next_cursor": "cJ0xNzg4MzU3MTEy"
}

limit defaults to 50, maximum 100. A larger value is clamped to the maximum rather than rejected.
next_cursor is null on the last page. It is the only end signal: do not infer the end from a short page.
A cursor is opaque with no guaranteed lifetime. Do not store it as a durable identifier, and do not build one yourself.
Ordering is stable within one pagination run. An item added while you are paging appears on your next full run, not in the middle of the current one.

GET/api/v1/railsPublished contract, not open

List payout methods

Payout rail catalogue with currency, countries served, p50 and p95 delays, business-day rules, cut-off, per-operation limits in minor units, fees and the beneficiary field schema. That schema is what lets you generate the payout form instead of coding it country by country.

Authentication: Authorization: Bearer … See authentication

Parameters

Parameters
Field	Type	Description
`country`	string	ISO 3166-1 alpha-2 filter.
`currency`	string	ISO 4217 filter.
`phase`	string	live, beta, planned or never.
`limit`	integer	Page size, 1 to 100, default 50.
`cursor`	string	Opaque cursor returned by the previous call.

Requestbash

curl -sS 'https://fiatside.com/api/v1/rails?country=BR' \
  -H 'Authorization: Bearer sk_live_...'

Response — published contractjson

{
  "data": [
    {
      "id": "br_pix",
      "slug": "pix",
      "name": "PIX",
      "kind": "instant_bank",
      "currency": "BRL",
      "countries": ["BR"],
      "phase": "live",
      "settlement": { "p50Minutes": 1, "p95Minutes": 10, "businessDaysOnly": false },
      "limits": { "minMinor": 1000, "maxMinor": 5000000, "decimals": 2 },
      "fees": { "fixedMinor": 0, "bps": 0 },
      "fields": [
        { "name": "pixKeyType", "type": "select", "required": true },
        { "name": "pixKey", "type": "text", "required": true, "maxLength": 77 },
        { "name": "taxId", "type": "text", "required": true, "pattern": "^[0-9]{11}$" }
      ],
      "verifiedAt": "2026-09-02"
    }
  ],
  "next_cursor": null
}

A closed rail is returned with its phase and reason, not removed from the list. An integration that cannot see why a rail vanished asks its own support.

Possible errors: unauthorized, invalid_request. Full catalogue

GET/api/v1/assetsPublished contract, not open

List accepted assets

Assets accepted for deposit, with base-unit decimals, networks, minimum deposit, rate lock duration and, where relevant, the reason an asset is not offered.

Authentication: Authorization: Bearer … See authentication

Parameters

Parameters
Field	Type	Description
`network`	string	Only returns assets available on that network.

Requestbash

curl -sS 'https://fiatside.com/api/v1/assets?network=tron' \
  -H 'Authorization: Bearer sk_live_...'

Response — published contractjson

{
  "data": [
    {
      "id": "usdt",
      "ticker": "USDT",
      "name": "Tether",
      "decimals": 6,
      "networks": ["tron", "ethereum", "bsc", "solana", "polygon", "arbitrum"],
      "stablecoin": true,
      "quoteLockSeconds": 1800,
      "minDepositBase": "20000000",
      "phase": "live"
    }
  ],
  "next_cursor": null
}

minDepositBase is expressed in BASE units (20000000 = 20 USDT at 6 decimals). Below that threshold the network cost eats most of the operation.

Possible errors: unauthorized. Full catalogue

GET/api/v1/countriesPublished contract, not open

List countries

Countries served, countries in preparation and refused countries. A refused country is returned with its reason: international sanctions, restrictive measures, or an unacceptable money laundering risk.

Authentication: Authorization: Bearer … See authentication

Parameters

Parameters
Field	Type	Description
`status`	string	open, coming or restricted.

Requestbash

curl -sS 'https://fiatside.com/api/v1/countries?status=open' \
  -H 'Authorization: Bearer sk_live_...'

Response — published contractjson

{
  "data": [
    { "code": "BR", "name": "Brasil", "currency": "BRL", "status": "open", "rails": ["br_pix", "paypal", "wise", "swift"] },
    { "code": "IR", "name": "Iran",   "currency": null,  "status": "restricted", "reason": "international_sanctions" }
  ],
  "next_cursor": null
}

Possible errors: unauthorized. Full catalogue

The beneficiary field schema

Every rail describes the fields it requires, with their validation pattern, normalisation and help text. That is what lets you generate a correct form for a country you have never integrated.

One schema fieldjson

{
  "name": "iban",
  "label": { "fr": "IBAN", "en": "IBAN" },
  "type": "iban",
  "required": true,
  "pattern": "^[A-Z]{2}[0-9]{2}[A-Z0-9]{11,30}$",
  "normalize": "upper",
  "help": {
    "fr": "Sans espaces. Nous verifions la cle de controle avant de valider la commande.",
    "en": "No spaces. We validate the checksum before confirming your order."
  }
}

Pattern validation happens on your side AND ours: yours saves the user a round trip, ours is authoritative. The help text is provided in both languages and deserves to be displayed: it prevents most rejected payouts, which almost always come from a mistyped format rather than an outage.