# Market data

Read candles, public trades, order books, and market overview, no credentials required.

Every service on this page is public. An unauthenticated client can call them.

```go
client, err := polyester.New(polyester.Config{HydrateCatalogs: true})
if err != nil { log.Fatal(err) }
defer client.Close()
if err := client.WaitForCatalogs(ctx); err != nil { log.Fatal(err) }
```

Streams use `Messages()` on typed subscriptions. Managed order-book / overview books use `Updates()`.

## Symbols

Prefer `"BTC-USDT"`. Resolve via catalogs after `WaitForCatalogs`, or pass `symbolID`.

## Market overview

```go
import "github.com/Fabric-Labs/polyester-sdk-go/services"

overview, err := client.MarketOverview.List(ctx, nil, 50, "", false)
sub, err := client.MarketOverview.CreateSubscription(ctx, services.MarketOverviewCreateSubscriptionOptions{
    Limit: 50,
})
for rows := range sub.Updates() { _ = rows; break }
```

## Candles

Alias: `client.Candles` → `client.MarketData`.

```go
symbol := "BTC-USDT"
result, err := client.Candles.GetCandles(ctx, &symbol, nil, "1h", 200, nil, nil, false)
sub, err := client.Candles.SubscribeCandles(ctx, &symbol, nil, "1m")
for c := range sub.Messages() { fmt.Println(c.Close); break }
```

Row candle results are newest-first, with an included open candle prepended; use index `0` for latest and reverse/sort by `TsSec` for indicators. Candle columns are oldest-first.

## Order book

```go
book, err := client.Orderbook.Get(ctx, "BTC-USDT", 20)
sub, err := client.Orderbook.CreateSubscription(ctx, services.CreateSubscriptionOptions{
    Symbol: "BTC-USDT",
    Depth:  50,
})
for b := range sub.Updates() { fmt.Println(b.BookSeq); break }
```

## Public trades

```go
symbol := "BTC-USDT"
tape, err := client.MarketData.GetTrades(ctx, &symbol, nil, 20, nil)
sub, err := client.MarketData.SubscribeTrades(ctx, &symbol, nil)
for t := range sub.Messages() { fmt.Println(t.Price); break }
```

Private fills are `client.Trades`, not the public tape.

## Heatmap & chain analytics

`client.Heatmap` and `client.ChainAnalytics` for L2 heatmap and chain analytics reads.

> **Streaming model**
>
> Centrifugo WebSocket + Protobuf. Details: [Streaming](https://testnet.polyester.com/docs/sdk/go/guides/streaming).

## Related

- [Order book](https://testnet.polyester.com/docs/sdk/go/reference/order-book) · [Candles](https://testnet.polyester.com/docs/sdk/go/reference/candles) · [Public trades](https://testnet.polyester.com/docs/sdk/go/reference/public-trades) · [Market overview](https://testnet.polyester.com/docs/sdk/go/reference/market-overview)