ccxt-compiled
Version:
A JavaScript / Python / PHP cryptocurrency trading library with support for 90+ exchanges
379 lines (310 loc) • 114 kB
Markdown
# Overview
The ccxt library is a collection of available crypto *exchanges* or exchange classes. Each class implements the public and private API for a particular crypto exchange. All exchanges are derived from the base Exchange class and share a set of common methods. To access a particular exchange from ccxt library you need to create an instance of corresponding exchange class. Supported exchanges are updated frequently and new exchanges are added regularly.
The structure of the library can be outlined as follows:
```
User
+-------------------------------------------------------------+
| CCXT |
+------------------------------+------------------------------+
| Public | Private |
+=============================================================+
│ . |
│ The Unified CCXT API |
│ . |
| loadMarkets . fetchBalance |
| fetchMarkets . createOrder |
| fetchTicker . cancelOrder |
| fetchTickers . fetchOrder |
| fetchOrderBook . fetchOrders |
| fetchOHLCV . fetchOpenOrders |
| fetchTrades . fetchClosedOrders |
| . fetchMyTrades |
| . deposit |
| . withdraw |
│ . |
+=============================================================+
│ . |
| Custom Exchange API |
| (Derived Classes) |
│ . |
| publicGet... . privateGet... |
| publicPost... . privatePost... |
| . privatePut... |
| . privateDelete... |
| . sign |
│ . |
+=============================================================+
│ . |
| Base Exchange Class |
│ . |
+=============================================================+
```
Full public and private HTTP REST APIs for all exchanges are implemented. WebSocket and FIX implementations in JavaScript, PHP, Python and other languages coming soon.
- [Exchanges](#exchanges)
- [Markets](#markets)
- [API Methods / Endpoints](#api-methods--endpoints)
- [Market Data](#market-data)
- [Trading](#trading)
# Exchanges
The ccxt library currently supports the following 94 cryptocurrency exchange markets and trading APIs:
| | id | name | ver | doc | countries |
|---------------------------------------------------------------------------------------------------------------------------|--------------------|-----------------------------------------------------------|:---:|:--------------------------------------------------------------------------------------------:|-----------------------------------------|
| | _1broker | [1Broker](https://1broker.com) | 2 | [API](https://1broker.com/?c=en/content/api-documentation) | US |
| | _1btcxe | [1BTCXE](https://1btcxe.com) | * | [API](https://1btcxe.com/api-docs.php) | Panama |
| | acx | [ACX](https://acx.io) | 2 | [API](https://acx.io/documents/api_v2) | Australia |
| | allcoin | [Allcoin](https://allcoin.com) | 1 | [API](https://allcoin.com/About/APIReference) | Canada |
| | anxpro | [ANXPro](https://anxpro.com) | 2 | [API](http://docs.anxv2.apiary.io) | Japan, Singapore, Hong Kong, New Zealand|
| | binance | [Binance](https://www.binance.com) | * | [API](https://github.com/binance-exchange/binance-official-api-docs/blob/master/rest-api.md) | China |
| | bit2c | [Bit2C](https://www.bit2c.co.il) | * | [API](https://www.bit2c.co.il/home/api) | Israel |
| | bitbay | [BitBay](https://bitbay.net) | * | [API](https://bitbay.net/public-api) | Poland, EU |
| | bitcoincoid | [Bitcoin.co.id](https://www.bitcoin.co.id) | 1.7 | [API](https://vip.bitcoin.co.id/downloads/BITCOINCOID-API-DOCUMENTATION.pdf) | Indonesia |
| | bitfinex | [Bitfinex](https://www.bitfinex.com) | 1 | [API](https://bitfinex.readme.io/v1/docs) | British Virgin Islands |
| | bitfinex2 | [Bitfinex v2](https://www.bitfinex.com) | 2 | [API](https://bitfinex.readme.io/v2/docs) | British Virgin Islands |
| | bitflyer | [bitFlyer](https://bitflyer.jp) | 1 | [API](https://bitflyer.jp/API) | Japan |
| | bithumb | [Bithumb](https://www.bithumb.com) | * | [API](https://www.bithumb.com/u1/US127) | South Korea |
| | bitlish | [Bitlish](https://bitlish.com) | 1 | [API](https://bitlish.com/api) | UK, EU, Russia |
| | bitmarket | [BitMarket](https://www.bitmarket.pl) | * | [API](https://www.bitmarket.net/docs.php?file=api_public.html) | Poland, EU |
| | bitmex | [BitMEX](https://www.bitmex.com) | 1 | [API](https://www.bitmex.com/app/apiOverview) | Seychelles |
| | bitso | [Bitso](https://bitso.com) | 3 | [API](https://bitso.com/api_info) | Mexico |
| | bitstamp | [Bitstamp](https://www.bitstamp.net) | 2 | [API](https://www.bitstamp.net/api) | UK |
| | bitstamp1 | [Bitstamp v1](https://www.bitstamp.net) | 1 | [API](https://www.bitstamp.net/api) | UK |
| | bittrex | [Bittrex](https://bittrex.com) | 1.1 | [API](https://bittrex.com/Home/Api) | US |
| | bl3p | [BL3P](https://bl3p.eu) | 1 | [API](https://github.com/BitonicNL/bl3p-api/tree/master/docs) | Netherlands, EU |
| | bleutrade | [Bleutrade](https://bleutrade.com) | 2 | [API](https://bleutrade.com/help/API) | Brazil |
| | btcbox | [BtcBox](https://www.btcbox.co.jp/) | 1 | [API](https://www.btcbox.co.jp/help/asm) | Japan |
| | btcchina | [BTCChina](https://www.btcchina.com) | 1 | [API](https://www.btcchina.com/apidocs) | China |
| | btcexchange | [BTCExchange](https://www.btcexchange.ph) | * | [API](https://github.com/BTCTrader/broker-api-docs) | Philippines |
| | btcmarkets | [BTC Markets](https://btcmarkets.net/) | * | [API](https://github.com/BTCMarkets/API) | Australia |
| | btctradeua | [BTC Trade UA](https://btc-trade.com.ua) | * | [API](https://docs.google.com/document/d/1ocYA0yMy_RXd561sfG3qEPZ80kyll36HUxvCRe5GbhE/edit) | Ukraine |
| | btcturk | [BTCTurk](https://www.btcturk.com) | * | [API](https://github.com/BTCTrader/broker-api-docs) | Turkey |
| | btcx | [BTCX](https://btc-x.is) | 1 | [API](https://btc-x.is/custom/api-document.html) | Iceland, US, EU |
| | bter | [Bter](https://bter.com) | 2 | [API](https://bter.com/api2) | British Virgin Islands, China |
| | bxinth | [BX.in.th](https://bx.in.th) | * | [API](https://bx.in.th/info/api) | Thailand |
| | ccex | [C-CEX](https://c-cex.com) | * | [API](https://c-cex.com/?id=api) | Germany, EU |
| | cex | [CEX.IO](https://cex.io) | * | [API](https://cex.io/cex-api) | UK, EU, Cyprus, Russia |
| | chbtc | [CHBTC](https://trade.chbtc.com/api) | 1 | [API](https://www.chbtc.com/i/developer) | China |
| | chilebit | [ChileBit](https://chilebit.net) | 1 | [API](https://blinktrade.com/docs) | Chile |
| | coincheck | [coincheck](https://coincheck.com) | * | [API](https://coincheck.com/documents/exchange/api) | Japan, Indonesia |
| | coinfloor | [coinfloor](https://www.coinfloor.co.uk) | * | [API](https://github.com/coinfloor/api) | UK |
| | coingi | [Coingi](https://coingi.com) | * | [API](http://docs.coingi.apiary.io/) | Panama, Bulgaria, China, US |
| | coinmarketcap | [CoinMarketCap](https://coinmarketcap.com) | 1 | [API](https://coinmarketcap.com/api) | US |
| | coinmate | [CoinMate](https://coinmate.io) | * | [API](http://docs.coinmate.apiary.io) | UK, Czech Republic |
| | coinsecure | [Coinsecure](https://coinsecure.in) | 1 | [API](https://api.coinsecure.in) | India |
| | coinspot | [CoinSpot](https://www.coinspot.com.au) | * | [API](https://www.coinspot.com.au/api) | Australia |
| | cryptopia | [Cryptopia](https://www.cryptopia.co.nz) | * | [API](https://www.cryptopia.co.nz/Forum/Category/45) | New Zealand |
| | dsx | [DSX](https://dsx.uk) | 3 | [API](https://api.dsx.uk) | UK |
| | exmo | [EXMO](https://exmo.me) | 1 | [API](https://exmo.me/en/api_doc) | Spain, Russia |
| | flowbtc | [flowBTC](https://trader.flowbtc.com) | 1 | [API](http://www.flowbtc.com.br/api/) | Brazil |
| | foxbit | [FoxBit](https://foxbit.exchange) | 1 | [API](https://blinktrade.com/docs) | Brazil |
| | fybse | [FYB-SE](https://www.fybse.se) | * | [API](http://docs.fyb.apiary.io) | Sweden |
| | fybsg | [FYB-SG](https://www.fybsg.com) | * | [API](http://docs.fyb.apiary.io) | Singapore |
| | gatecoin | [Gatecoin](https://gatecoin.com) | * | [API](https://gatecoin.com/api) | Hong Kong |
| | gateio | [Gate.io](https://gate.io/) | 2 | [API](https://gate.io/api2) | China |
| | gdax | [GDAX](https://www.gdax.com) | * | [API](https://docs.gdax.com) | US |
| | gemini | [Gemini](https://gemini.com) | 1 | [API](https://docs.gemini.com/rest-api) | US |
| | getbtc | [GetBTC](https://getbtc.org) | * | [API](https://getbtc.org/api-docs.php) | St. Vincent & Grenadines, Russia |
| | hitbtc | [HitBTC](https://hitbtc.com) | 1 | [API](https://github.com/hitbtc-com/hitbtc-api/blob/master/APIv1.md) | Hong Kong |
| | hitbtc2 | [HitBTC v2](https://hitbtc.com) | 2 | [API](https://api.hitbtc.com) | Hong Kong |
| | huobi | [Huobi](https://www.huobi.com) | 3 | [API](https://github.com/huobiapi/API_Docs_en/wiki) | China |
| | huobicny | [Huobi CNY](https://www.huobi.com) | 1 | [API](https://github.com/huobiapi/API_Docs/wiki/REST_api_reference) | China |
| | huobipro | [Huobi Pro](https://www.huobi.pro) | 1 | [API](https://github.com/huobiapi/API_Docs/wiki/REST_api_reference) | China |
| | independentreserve | [Independent Reserve](https://www.independentreserve.com) | * | [API](https://www.independentreserve.com/API) | Australia, New Zealand |
| | itbit | [itBit](https://www.itbit.com) | 1 | [API](https://api.itbit.com/docs) | US |
| | jubi | [jubi.com](https://www.jubi.com) | 1 | [API](https://www.jubi.com/help/api.html) | China |
| | kraken | [Kraken](https://www.kraken.com) | 0 | [API](https://www.kraken.com/en-us/help/api) | US |
| | kucoin | [Kucoin](https://kucoin.com) | 1 | [API](https://kucoinapidocs.docs.apiary.io) | Hong Kong |
| | kuna | [Kuna](https://kuna.io) | 2 | [API](https://kuna.io/documents/api) | Ukraine |
| | lakebtc | [LakeBTC](https://www.lakebtc.com) | 2 | [API](https://www.lakebtc.com/s/api_v2) | US |
| | liqui | [Liqui](https://liqui.io) | 3 | [API](https://liqui.io/api) | Ukraine |
| | livecoin | [LiveCoin](https://www.livecoin.net) | * | [API](https://www.livecoin.net/api?lang=en) | US, UK, Russia |
| | luno | [luno](https://www.luno.com) | 1 | [API](https://www.luno.com/en/api) | UK, Singapore, South Africa |
| | mercado | [Mercado Bitcoin](https://www.mercadobitcoin.com.br) | 3 | [API](https://www.mercadobitcoin.com.br/api-doc) | Brazil |
| | mixcoins | [MixCoins](https://mixcoins.com) | 1 | [API](https://mixcoins.com/help/api/) | UK, Hong Kong |
| | nova | [Novaexchange](https://novaexchange.com) | 2 | [API](https://novaexchange.com/remote/faq) | Tanzania |
| | okcoincny | [OKCoin CNY](https://www.okcoin.cn) | 1 | [API](https://www.okcoin.cn/rest_getStarted.html) | China |
| | okcoinusd | [OKCoin USD](https://www.okcoin.com) | 1 | [API](https://www.okcoin.com/rest_getStarted.html) | China, US |
| | okex | [OKEX](https://www.okex.com) | 1 | [API](https://www.okex.com/rest_getStarted.html) | China, US |
| | paymium | [Paymium](https://www.paymium.com) | 1 | [API](https://github.com/Paymium/api-documentation) | France, EU |
| | poloniex | [Poloniex](https://poloniex.com) | * | [API](https://poloniex.com/support/api/) | US |
| | qryptos | [QRYPTOS](https://www.qryptos.com) | 2 | [API](https://developers.quoine.com) | China, Taiwan |
| | quadrigacx | [QuadrigaCX](https://www.quadrigacx.com) | 2 | [API](https://www.quadrigacx.com/api_info) | Canada |
| | quoine | [QUOINE](https://www.quoine.com) | 2 | [API](https://developers.quoine.com) | Japan, Singapore, Vietnam |
| | southxchange | [SouthXchange](https://www.southxchange.com) | * | [API](https://www.southxchange.com/Home/Api) | Argentina |
| | surbitcoin | [SurBitcoin](https://surbitcoin.com) | 1 | [API](https://blinktrade.com/docs) | Venezuela |
| | therock | [TheRockTrading](https://therocktrading.com) | 1 | [API](https://api.therocktrading.com/doc/v1/index.html) | Malta |
| | tidex | [Tidex](https://tidex.com) | 3 | [API](https://tidex.com/public-api) | UK |
| | urdubit | [UrduBit](https://urdubit.com) | 1 | [API](https://blinktrade.com/docs) | Pakistan |
| | vaultoro | [Vaultoro](https://www.vaultoro.com) | 1 | [API](https://api.vaultoro.com) | Switzerland |
| | vbtc | [VBTC](https://vbtc.exchange) | 1 | [API](https://blinktrade.com/docs) | Vietnam |
| | virwox | [VirWoX](https://www.virwox.com) | * | [API](https://www.virwox.com/developers.php) | Austria, EU |
| | wex | [WEX](https://wex.nz) | 3 | [API](https://wex.nz/api/3/docs) | New Zealand |
| | xbtce | [xBTCe](https://www.xbtce.com) | 1 | [API](https://www.xbtce.com/tradeapi) | Russia |
| | yobit | [YoBit](https://www.yobit.net) | 3 | [API](https://www.yobit.net/en/api/) | Russia |
| | yunbi | [YUNBI](https://yunbi.com) | 2 | [API](https://yunbi.com/documents/api/guide) | China |
| | zaif | [Zaif](https://zaif.jp) | 1 | [API](http://techbureau-api-document.readthedocs.io/ja/latest/index.html) | Japan |
| | zb | [ZB](https://trade.zb.com/api) | 1 | [API](https://www.zb.com/i/developer) | China |
Besides making basic market and limit orders, some exchanges offer margin trading (leverage), various derivatives (like futures contracts and options) and also have [dark pools](https://en.wikipedia.org/wiki/Dark_pool), [OTC](https://en.wikipedia.org/wiki/Over-the-counter_(finance)) (over-the-counter trading), merchant APIs and much more.
## Instantiation
To connect to an exchange and start trading you need to instantiate an exchange class from ccxt library.
To get the full list of ids of supported exchanges programmatically:
```JavaScript
// JavaScript
const ccxt = require ('ccxt')
console.log (ccxt.exchanges)
```
```Python
# Python
import ccxt
print (ccxt.exchanges)
```
```PHP
// PHP
include 'ccxt.php';
var_dump (\ccxt\Exchange::$exchanges);
```
An exchange can be instantiated like shown in the examples below:
```JavaScript
// JavaScript
const ccxt = require ('ccxt')
let exchange = new ccxt.kraken () // default id
let kraken1 = new ccxt.kraken ({ id: 'kraken1' })
let kraken2 = new ccxt.kraken ({ id: 'kraken2' })
let id = 'gdax'
let gdax = new ccxt[id] ();
```
```Python
# Python
import ccxt
exchange = ccxt.okcoinusd () # default id
okcoin1 = ccxt.okcoinusd ({ 'id': 'okcoin1' })
okcoin2 = ccxt.okcoinusd ({ 'id': 'okcoin2' })
id = 'btcchina'
btcchina = eval ('ccxt.%s ()' % id)
gdax = getattr (ccxt, 'gdax') ()
```
The ccxt library in PHP uses builtin UTC/GMT time functions, therefore you are required to set date.timezone in your php.ini or call [date_default_timezone_set ()](http://php.net/manual/en/function.date-default-timezone-set.php) function before using the PHP version of the library. The recommended timezone setting is `"UTC"`.
```PHP
// PHP
date_default_timezone_set ('UTC');
include 'ccxt.php';
$bitfinex = new \ccxt\bitfinex (); // default id
$bitfinex1 = new \ccxt\bitfinex (array ('id' => 'bitfinex1'));
$bitfinex2 = new \ccxt\bitfinex (array ('id' => 'bitfinex2'));
$id = 'kraken';
$kraken = new \ccxt\$id ();
```
## Exchange Structure
Every exchange has a set of properties and methods, most of which you can override by passing an associative array of params to an exchange constructor. You can also make a subclass and override everything.
Here's an overview of base exchange properties with values added for example:
```JavaScript
{
'id': 'exchange' // lowercase string exchange id
'name': 'Exchange' // human-readable string
'countries': [ 'US', 'CN', 'EU' ], // string or array of ISO country codes
'urls': {
'api': 'https://api.example.com/data', // string or dictionary of base API URLs
'www': 'https://www.example.com' // string website URL
'doc': 'https://docs.example.com/api', // string URL or array of URLs
},
'version': 'v1', // string ending with digits
'api': { ... }, // dictionary of api endpoints
'hasFetchTickers': true, // true if the exchange implements fetchTickers ()
'hasFetchOHLCV': false, // true if the exchange implements fetchOHLCV ()
'timeframes': { // empty if the exchange !hasFetchOHLCV
'1m': '1minute',
'1h': '1hour',
'1d': '1day',
'1M': '1month',
'1y': '1year',
},
'timeout': 10000, // number in milliseconds
'rateLimit': 2000, // number in milliseconds
'userAgent': 'ccxt/1.1.1 ...' // string, HTTP User-Agent header
'verbose': false, // boolean, output error details
'markets': { ... } // dictionary of markets/pairs by symbol
'symbols': [ ... ] // sorted list of string symbols (traded pairs)
'currencies': { ... } // dictionary of currencies by currency code
'markets_by_id': { ... }, // dictionary of dictionaries (markets) by id
'proxy': 'https://crossorigin.me/', // string URL
'apiKey': '92560ffae9b8a0421...', // string public apiKey (ASCII, hex, Base64, ...)
'secret': '9aHjPmW+EtRRKN/Oi...' // string private secret key
'password': '6kszf4aci8r', // string password
'uid': '123456', // string user id
}
```
### Exchange Properties
Below is a detailed description of each of the base exchange properties:
- `id`: Each exchange has a default id. The id is not used for anything, it's a string literal for user-land exchange instance identification purposes. You can have multiple links to the same exchange and differentiate them by ids. Default ids are all lowercase and correspond to exchange names.
- `name`: This is a string literal containing the human-readable exchange name.
- `countries`: A string literal or an array of string literals of 2-symbol ISO country codes, where the exchange is operating from.
- `urls['api']`: The single string literal base URL for API calls or an associative array of separate URLs for private and public APIs.
- `urls['www']`: The main HTTP website URL.
- `urls['doc']`: A single string URL link to original documentation for exchange API on their website or an array of links to docs.
- `version`: A string literal containing version identifier for current exchange API. The ccxt library will append this version string to the API Base URL upon each request. You don't have to modify it, unless you are implementing a new exchange API. The version identifier is a usually a numeric string starting with a letter 'v' in some cases, like v1.1. Do not override it unless you are implementing your own new crypto exchange class.
- `api`: An associative array containing a definition of all API endpoints exposed by a crypto exchange. The API definition is used by ccxt to automatically construct callable instance methods for each available endpoint.
- `hasFetchTickers`: This is a boolean property indicating if the exchange has the fetchTickers () method available. When this property is false, the exchange will also throw a NotSupported exception upon a call to fetchTickers ().
- `hasFetchOHLCV`: This is a boolean property indicating if the exchange has the fetchOHLCV () method available. When this property is false, the exchange will also throw a NotSupported exception upon a call to fetchOHLCV (). Also, if this property is true, the `timeframes` property is populated as well.
- `timeframes`: An associative array of timeframes, supported by the fetchOHLCV method of the exchange. This is only populated when `hasFetchTickers` property is true.
- `timeout`: A timeout in milliseconds for a request-response roundtrip (default timeout is 10000 ms = 10 seconds). You should always set it to a reasonable value, hanging forever with no timeout is not your option, for sure.
- `rateLimit`: A request rate limit in milliseconds. Specifies the required minimal delay between two consequent HTTP requests to the same exchange. This parameter is not used for now (reserved for future).
- `userAgent`: An object to set HTTP User-Agent header to. The ccxt library will set its User-Agent by default. Some exchanges may not like it. If you are having difficulties getting a reply from an exchange and want to turn User-Agent off or use the default one, set this value to false, undefined, or an empty string.
- `verbose`: A boolean flag indicating whether to log HTTP requests to stdout (verbose flag is false by default).
- `markets`: An associative array of markets indexed by common trading pairs or symbols. Markets should be loaded prior to accessing this property. Markets are unavailable until you call the `loadMarkets() / load_markets()` method on exchange instance.
- `symbols`: A non-associative array (a list) of symbols available with an exchange, sorted in alphabetical order. These are the keys of the `markets` property. Symbols are loaded and reloaded from markets. This property is a convenient shorthand for all market keys.
- `currencies`: An associative array (a dict) of currencies by codes (usually 3 or 4 letters) available with an exchange. Currencies are loaded and reloaded from markets.
- `markets_by_id`: An associative array of markets indexed by exchange-specific ids. Markets should be loaded prior to accessing this property.
- `proxy`: A string literal containing base URL of http(s) proxy, `''` by default. For use with web browsers and from blocked locations. An example of a proxy string is `'http://crossorigin.me/'`. The absolute exchange endpoint URL is appended to this string before sending the HTTP request.
- `apiKey`: This is your public API key string literal. Most exchanges require this for trading ([see below](https://github.com/ccxt/ccxt/wiki/Manual#api-keys-setup)).
- `secret`: Your private secret API key string literal. Most exchanges require this as well together with the apiKey.
- `password`: A string literal with your password/phrase. Some exchanges require this parameter for trading, but most of them don't.
- `uid`: A unique id of your account. This can be a string literal or a number. Some exchanges also require this for trading, but most of them don't.
## Rate Limit
Exchanges usually impose what is called a *rate limit*. Exchanges will remember and track your user credentials and your IP address and will not allow you to query the API too frequently. They balance their load and control traffic congestion to protect API servers from (D)DoS and misuse.
**WARNING: Stay under the rate limit to avoid ban!**
Most exchanges allow **up to 1 or 2 requests per second**. Exchanges may temporarily restrict your access to their API or ban you for some period of time if you are too aggressive with your requests.
### DDoS Protection By Cloudflare / Incapsula
Some exchanges are [DDoS](https://en.wikipedia.org/wiki/Denial-of-service_attack)-protected by [Cloudflare](https://www.cloudflare.com) or [Incapsula](https://www.incapsula.com). Your IP can get temporarily blocked during periods of high load. Sometimes they even restrict whole countries and regions. In that case their servers usually return a page that states a HTTP 40x error or runs an AJAX test of your browser / captcha test and delays the reload of the page for several seconds. Then your browser/fingerprint is granted access temporarily and gets added to a whitelist or receives a HTTP cookie for further use.
If you encounter DDoS protection errors and cannot reach a particular exchange then:
- try later
- use a proxy (this is less responsive, though)
- ask the exchange support to add you to a whitelist
- run your software in close proximity to the exchange (same country, same city, same datacenter, same server rack, same server)
- try an alternative IP within a different geographic region
- run your software in a distributed network of servers
- ...
In case your calls hit a rate limit or get nonce errors, the ccxt library will throw an exception of one of the following types:
- DDoSProtectionError
- ExchangeNotAvailable
- ExchangeError
A later retry is usually enough to handle that. More on that here:
- [Authentication](https://github.com/ccxt/ccxt/wiki/Manual#authentication)
- [Troubleshooting](https://github.com/ccxt/ccxt/wiki/Manual#troubleshooting)
- [Overriding The Nonce](https://github.com/ccxt/ccxt/wiki/Manual#overriding-the-nonce)
# Markets
Each exchange is a place for trading some kinds of valuables. Sometimes they are called with various different terms like instruments, symbols, trading pairs, currencies, tokens, stocks, commodities, contracts, etc, but they all mean the same – a trading pair, a symbol or a financial instrument.
In terms of the ccxt library, every exchange offers multiple markets within itself. The set of markets differs from exchange to exchange opening possibilities for cross-exchange and cross-market arbitrage. A market is usually a pair of traded crypto/fiat currencies.
## Market Structure
```JavaScript
{
'id': 'btcusd', // string literal for referencing within an exchange
'symbol': 'BTC/USD', // uppercase string literal of a pair of currencies
'base': 'BTC', // uppercase string, base currency, 3 or more letters
'quote': 'USD', // uppercase string, quote currency, 3 or more letters
'precision': { // number of decimal digits "after the dot"
'price': 8, // integer
'amount': 8, // integer
'cost': 8, // integer
},
'limits': { // value limits when placing orders on this market
'amount': {
'min': 0.01, // order amount should be > min
'max': 1000, // order amount should be < max
},
'price': { ... }, // same min/max limits for the price of the order
'cost': { ... }, // same limits for order cost = price * amount
}
'info': { ... }, // the original unparsed market info from the exchange
}
```
Each market is an associative array (aka dictionary) with the following keys:
- `id`. The string or numeric ID