|BUSINESS API

One signed REST API to create crypto exchanges from inside your own product. Set your markup, keep it as revenue, and let Fujn handle live pricing, settlement and on-chain tracking. HMAC-signed, predictable JSON, and a request model your team can integrate in an afternoon.

Generate your API key

Introduction

The Fujn Business API gives your product programmatic access to live rates and instant exchange orders, with the same execution quality Fujn runs on. You quote, you create, you track. Every order carries the markup you set on top of our rate, and that markup is yours, paid out as revenue.

To use the API you need an API key and an API secret. Requesting a key enrols you in the affiliate program automatically, so earnings, balance and payouts all live in one dashboard.

Getting your key

1Sign in to Fujn and open the affiliate dashboard.
2Go to the API tab and submit the service you will integrate, together with your markup.
3An admin reviews every request. Once approved, your key can create live orders and you are notified by email.
4Copy your API key and secret and keep them safe. The secret is shown only once.

Open API management

Authentication

Data is sent as JSON with UTF-8 encoding. Every request must carry these headers:

Base URLhttps://api.fujn.com/api/v1

Content-Typeapplication/json; charset=UTF-8

X-API-KEYyour public API key

X-API-SIGNhmac_sha256(raw_json_body, your_secret)

The X-API-SIGN header is an HMAC-SHA256 signature of the exact JSON body string, keyed with your API secret, in hex. Always sign the precise bytes you send. For requests without a body, sign an empty JSON object.

# Build the body, sign it with your secret, then send it.
BODY='{"type":"float","fromCcy":"BTC","toCcy":"ETH","direction":"from","amount":0.1,"toAddress":"0xYourAddress"}'

SIGN=$(printf '%s' "$BODY" | openssl dgst -sha256 -hmac "$API_SECRET" | sed 's/^.* //')

curl -X POST "https://api.fujn.com/api/v1/create" \
  -H "X-API-KEY: $API_KEY" \
  -H "X-API-SIGN: $SIGN" \
  -H "Content-Type: application/json; charset=UTF-8" \
  -d "$BODY"

Request limits

The request limit is 250 weight units per minute. The /v1/create request costs 50 weight units, every other request costs 1 weight unit. If you exceed the limit your key is temporarily throttled, and the wait grows on each repeat.

POST/v1/ccies1 weight unit

List the currencies and networks Fujn supports, with availability for sending and receiving.

Response

{
  "code": 0,
  "msg": "",
  "data": [
    {
      "code": "BTC",
      "coin": "BTC",
      "network": "BTC",
      "name": "Bitcoin",
      "recv": true,
      "send": true,
      "tag": null,
      "logo": "https://assets.fujn.com/images/coins/svg/btc.svg",
      "color": "#f7931a"
    }
  ]
}

POST/v1/price1 weight unit

Get a quote for a pair: the rate, the receive amount, and the minimum and maximum for the exchange. Pass afftax to add your markup.

Name	Type	Required	Description
`type`	string	yes	"fixed" or "float".
`fromCcy`	string	yes	Code of the currency the client sends.
`toCcy`	string	yes	Code of the currency the client receives.
`direction`	string	yes	"from" if amount is the send amount, "to" if it is the receive amount.
`amount`	number	yes	The amount, read per direction.
`afftax`	number	no	Your markup percentage, added on top of our rate.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "from": { "code": "BTC", "amount": 0.1, "rate": 17.72, "min": 0.0004, "max": 1.51 },
    "to":   { "code": "ETH", "amount": 1.7715, "rate": 0.0564 },
    "errors": []
  }
}

POST/v1/create50 weight units

Create an exchange order for a pair, amount and destination address. The response includes the deposit address and an order token used to track it.

Name	Type	Required	Description
`type`	string	yes	"fixed" or "float".
`fromCcy`	string	yes	Code of the currency the client sends.
`toCcy`	string	yes	Code of the currency the client receives.
`direction`	string	yes	"from" or "to".
`amount`	number	yes	The amount, read per direction.
`toAddress`	string	yes	Destination address the exchanged funds are sent to.
`tag`	string	no	MEMO or destination tag, if the receiving address needs one.
`afftax`	number	no	Your markup percentage, paid to you as earnings.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "id": "FJ7C2A9E4B1D8F",
    "type": "float",
    "status": "NEW",
    "token": "a1b2c3d4...your_order_token",
    "from": {
      "code": "BTC",
      "amount": "0.10000000",
      "address": "bc1qm8e58htm6qlhz5u7awhe4a5kxt3w86ffwtl9j0",
      "tag": null
    },
    "to": {
      "code": "ETH",
      "amount": "1.77150000",
      "address": "0xYourDestinationAddress"
    },
    "time": { "reg": 1676458603, "expiration": 1676460403, "left": 1800 }
  }
}

POST/v1/order1 weight unit

Fetch the live status of an order. Use the id and the token returned by create.

Name	Type	Required	Description
`id`	string	yes	Order ID.
`token`	string	yes	Order security token from create.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "id": "FJ7C2A9E4B1D8F",
    "status": "PENDING",
    "from": { "code": "BTC", "amount": "0.10000000" },
    "to":   { "code": "ETH", "amount": "1.77150000" }
  }
}

Errors

Every response carries a code and a msg. A code of 0 means success. Any other value is an error, with a readable reason in msg and the matching HTTP status.

{ "code": 4, "msg": "Pair BTC to XYZ is not supported", "data": null }

code	HTTP	Meaning
`0`	200	Success.
`1`	401	Authentication failed: missing or invalid X-API-KEY or X-API-SIGN.
`2`	403	API key is not active: pending approval, suspended or blocked.
`3`	400	Invalid request: a required field is missing or malformed.
`4`	400	Unsupported currency or pair.
`5`	422	Amount is below the minimum or above the maximum.
`6`	502	Could not generate a deposit address. Please retry.
`7`	503	Exchange temporarily unavailable.
`8`	429	Rate limit exceeded.

Your earnings

You set a markup on top of our base rate, up to 5%. That markup is yours. It accrues to your affiliate balance for every order you create through the API, and you withdraw it from the same dashboard. Requesting an API key enrols you automatically.

Open API management

Earn $50

Authenticating...

|BUSINESS API

Generate your API key

Introduction

To use the API you need an API key and an API secret. Requesting a key enrols you in the affiliate program automatically, so earnings, balance and payouts all live in one dashboard.

Getting your key

1Sign in to Fujn and open the affiliate dashboard.
2Go to the API tab and submit the service you will integrate, together with your markup.
3An admin reviews every request. Once approved, your key can create live orders and you are notified by email.
4Copy your API key and secret and keep them safe. The secret is shown only once.

Open API management

Authentication

Data is sent as JSON with UTF-8 encoding. Every request must carry these headers:

Base URLhttps://api.fujn.com/api/v1

Content-Typeapplication/json; charset=UTF-8

X-API-KEYyour public API key

X-API-SIGNhmac_sha256(raw_json_body, your_secret)

# Build the body, sign it with your secret, then send it.
BODY='{"type":"float","fromCcy":"BTC","toCcy":"ETH","direction":"from","amount":0.1,"toAddress":"0xYourAddress"}'

SIGN=$(printf '%s' "$BODY" | openssl dgst -sha256 -hmac "$API_SECRET" | sed 's/^.* //')

curl -X POST "https://api.fujn.com/api/v1/create" \
  -H "X-API-KEY: $API_KEY" \
  -H "X-API-SIGN: $SIGN" \
  -H "Content-Type: application/json; charset=UTF-8" \
  -d "$BODY"

Request limits

POST/v1/ccies1 weight unit

List the currencies and networks Fujn supports, with availability for sending and receiving.

Response

{
  "code": 0,
  "msg": "",
  "data": [
    {
      "code": "BTC",
      "coin": "BTC",
      "network": "BTC",
      "name": "Bitcoin",
      "recv": true,
      "send": true,
      "tag": null,
      "logo": "https://assets.fujn.com/images/coins/svg/btc.svg",
      "color": "#f7931a"
    }
  ]
}

POST/v1/price1 weight unit

Get a quote for a pair: the rate, the receive amount, and the minimum and maximum for the exchange. Pass afftax to add your markup.

Name	Type	Required	Description
`type`	string	yes	"fixed" or "float".
`fromCcy`	string	yes	Code of the currency the client sends.
`toCcy`	string	yes	Code of the currency the client receives.
`direction`	string	yes	"from" if amount is the send amount, "to" if it is the receive amount.
`amount`	number	yes	The amount, read per direction.
`afftax`	number	no	Your markup percentage, added on top of our rate.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "from": { "code": "BTC", "amount": 0.1, "rate": 17.72, "min": 0.0004, "max": 1.51 },
    "to":   { "code": "ETH", "amount": 1.7715, "rate": 0.0564 },
    "errors": []
  }
}

POST/v1/create50 weight units

Create an exchange order for a pair, amount and destination address. The response includes the deposit address and an order token used to track it.

Name	Type	Required	Description
`type`	string	yes	"fixed" or "float".
`fromCcy`	string	yes	Code of the currency the client sends.
`toCcy`	string	yes	Code of the currency the client receives.
`direction`	string	yes	"from" or "to".
`amount`	number	yes	The amount, read per direction.
`toAddress`	string	yes	Destination address the exchanged funds are sent to.
`tag`	string	no	MEMO or destination tag, if the receiving address needs one.
`afftax`	number	no	Your markup percentage, paid to you as earnings.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "id": "FJ7C2A9E4B1D8F",
    "type": "float",
    "status": "NEW",
    "token": "a1b2c3d4...your_order_token",
    "from": {
      "code": "BTC",
      "amount": "0.10000000",
      "address": "bc1qm8e58htm6qlhz5u7awhe4a5kxt3w86ffwtl9j0",
      "tag": null
    },
    "to": {
      "code": "ETH",
      "amount": "1.77150000",
      "address": "0xYourDestinationAddress"
    },
    "time": { "reg": 1676458603, "expiration": 1676460403, "left": 1800 }
  }
}

POST/v1/order1 weight unit

Fetch the live status of an order. Use the id and the token returned by create.

Name	Type	Required	Description
`id`	string	yes	Order ID.
`token`	string	yes	Order security token from create.

Response

{
  "code": 0,
  "msg": "",
  "data": {
    "id": "FJ7C2A9E4B1D8F",
    "status": "PENDING",
    "from": { "code": "BTC", "amount": "0.10000000" },
    "to":   { "code": "ETH", "amount": "1.77150000" }
  }
}

Errors

Every response carries a code and a msg. A code of 0 means success. Any other value is an error, with a readable reason in msg and the matching HTTP status.

{ "code": 4, "msg": "Pair BTC to XYZ is not supported", "data": null }

code	HTTP	Meaning
`0`	200	Success.
`1`	401	Authentication failed: missing or invalid X-API-KEY or X-API-SIGN.
`2`	403	API key is not active: pending approval, suspended or blocked.
`3`	400	Invalid request: a required field is missing or malformed.
`4`	400	Unsupported currency or pair.
`5`	422	Amount is below the minimum or above the maximum.
`6`	502	Could not generate a deposit address. Please retry.
`7`	503	Exchange temporarily unavailable.
`8`	429	Rate limit exceeded.

Your earnings

Open API management

Introduction

Getting your key

Authentication

Request limits

Errors

Your earnings

LOADING

Introduction

Getting your key

Authentication

Request limits

Errors

Your earnings