Estimate fixed rate exchange

Method returns a fixed exchange estimation for the provided amount. It needs an additional parameter amountFrom or amountTo to estimate a fixed exchange result.

So, the main difference between getFixRateForAmount and getFixRate methods is that getFixRateForAmount fetches fixed amount based on the additional amountFrom or amountTo parameter.

info

Before getting the fixed rate for specific amount, you need to ensure that your amount is greater or equal than minimal amount and less or equal than maximal amount. For this, you need to call getPairsParams method for fetching minimal and maximal amount for a current pair.

If amount will not correspond with the minimal and maximal range for amount, the request will result in error: see the sample error response in the right section.

warning

Although amountFrom and amountTo are optional parameters, it is required to set one of them. If you provide none or both, the request will result in error.

HTTP request

post

/v2/#getFixRateForAmount

Request

Header parameters

Requires authentification.

Body parameters

Requires JSON-RPC 2.0 protocol request body.

info

You can set params as:

an object to get result for 1 currency pair
an array of 1 object to get result even if you request only 1 currency pair
an array of objects when requesting more than 1 currency pair

If you set params as an object without an array, getFixRateForAmount will return an error.
If you set params as an object in an array, getExchangeAmount will return an array without an invalid currency pair or an empty array.

The params parameter schema:

Name	Type	Required	Description
from	string	true	Payin currency ticker (in lowercase).
to	string	true	Payout currency ticker (in lowercase).
amountFrom	string	false	Amount that user is going to exchange.
amountTo	string	false	Amount that user is going to receive.
userMetadata	string	false	Escaped JSON. You can use `userMetadata` to include any additional parameters for customization purposes. To use this feature, please contact us at [email protected].

Sample request payload

application/json
{
  "jsonrpc": "2.0",
  "id": "test",
  "method": "getFixRateForAmount",
  "params": [
    {
      "from": "eth",
      "to": "btc",
      "amountFrom": "5.2"
    },
    {
      "from": "btc",
      "to": "eth",
      "amountTo": "2.25"
    }
  ]
}

Sample request payload with the userMetadata

application/json
{
"jsonrpc": "2.0",
"id": "test",
"method": "getFixRateForAmount",
"params": [
  {
    "from": "eth",
    "to": "btc",
    "amountFrom": "5.2",
    "userMetadata": "{\"param1\": 50, \"param2\": \"string\", \"param3\": \"50.5189\"}"
  },
  {
    "from": "btc",
    "to": "eth",
    "amountTo": "2.25",
    "userMetadata": "{\"param1\": 50, \"param2\": \"string\", \"param3\": \"50.5189\"}"
  }
]
}

Sample cURL

curl --location --request POST 'https://api.changelly.com/v2' \
--header 'X-Api-Key: {{apiKey}}' \
--header 'X-Api-Signature: {{sign}}' \
--data-raw '{
  "id": "test",
  "jsonrpc": "2.0",
  "method": "getFixRateForAmount",
  "params": [
    {
      "from": "eth",
      "to": "btc",
      "amountFrom": "5.2"
    },
    {
      "from": "btc",
      "to": "eth",
      "amountTo": "2.25"
    }
  ]
}'

Response

Response parameters

Requires JSON-RPC 2.0 protocol response body.

The result parameter schema:

Name	Type	Description
id	string	Rate ID that can be used during 1 minute. This time should be enough for user to initiate the exchange. Expired rate `id` cannot be used for creation of the fixed rate transaction. `id` has to be stored somewhere. It will be used as `rateId` value while calling.
result	string	Exchange rate before withholding the network fee. Important. To calculate the exact amount that the user will get, you need to multiply the amount that the user wants to send to the `result` and deduct the value of the `networkFee`.
from	string	Payin currency ticker.
to	string	Payout currency ticker.
networkFee	string	Commission taken by the network from the amount sent to the user. Displayed in pay-out currency.
max	string	Maximum exchangeable amount.
maxFrom	string	Maximum payin amount for which we would be able to perform the exchange.
maxTo	string	Maximum payout amount for which we would be able to perform the exchange.
min	string	Minimum exchangeable amount.
minFrom	string	Minimum payin amount for which we would be able to perform the exchange.
minTo	string	Minimum payout amount for which we would be able to perform the exchange.
amountFrom	string	Amount of assets that user will exchange after creating a fixed rate transaction.
amountTo	string	Fixed exchange amount that user will receive after finishing a fixed-rate transaction using current `rateId`.
expiredAt	integer	Unix timestamp in seconds (10 digits) representing the expiration time of the fixed rate.

Sample response

application/json
{
  "jsonrpc": "2.0",
  "id": "test",
  "result": [
    {
      "id": "f4dd43106d63b65b88955a0b36******ffb7a8480dd32e799431177f",
      "result": "0.02556948",
      "networkFee": "0.000175",
      "from": "eth",
      "to": "btc",
      "max": "50.000000000000000000",
      "maxFrom": "50.000000000000000000",
      "maxTo": "1.27847400",
      "min": "0.148414210000000000",
      "minFrom": "0.148414210000000000",
      "minTo": "0.00379488",
      "amountFrom": "5.2",
      "amountTo": "0.34047438",
      "expiredAt": 1664890979
    }
  ]
}

Error response

Error response parameters

Check the error response schema.

Error codes

Code	Message	Description
`-32600`	`Error: You reached requests limit {limit} rps`	You have been sending more than 10 requests per second.
`-32602`	`Invalid amount for pair {from_currency}->{to_currency}`	The attempt to exchange more currency than a maximal amount or less than the minimal one.
`-32602`	`Invalid amount for pair {from_currency}->{to_currency}. {limit_type} amount is {limit} {currency}`	The attempt to exchange currency out of limits. `{limit_type}` is a “Minimal“ or “Maximum“ value.
`-32602`	`Invalid currency: {currency} temporary disabled`	This currency is currently disabled.
`-32602`	`Invalid currency: {currency} temporary disabled for fix rate transactions`	This currency is currently disabled for fix-rate transactions.
`-32602`	`Invalid currency: {currency} is temporary disabled on API as output currency`	This currency is currently disabled on API as an output currency.
`-32602`	`Invalid currency: {currency} is temporary disabled on API as input currency`	This currency is currently disabled on API as an input currency.
`-32602`	`Invalid currency: {currency} not found`	This currency is not listed on Changelly or the ticker is invalid.
`-32602`	`Parameter {param} is invalid`	You've specified an invalid parameter.
`-32603`	`Internal Error` or `Error`	Most likely, the problem is on our side. Further investigation is required.

Estimate fixed rate exchange

HTTP request​

Request​

Header parameters​

Body parameters​

Response​

Response parameters​

Error response​

Error response parameters​

Error codes​