> ## Documentation Index
> Fetch the complete documentation index at: https://docs.spreader.sh/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Spreader is a web service that tracks arbitrage spreads between crypto exchanges. This documentation covers only what a user of the service sees and does.
> Page paths starting with /en/ are English. Translations live under /ru/ and /uk/ with the same file names.
> Screenshots are illustrations. Every screenshot is accompanied by text that states the same facts, so you do not need to see the image.

# Pair builder

> Pair builder opens the spread page of any two markets of one asset, including pairs the scanner does not list: pick the asset, tick the long and the short market, click Open spread.

Open **Tools › Pair builder** or go to `/tools/pair`. With an asset chosen the address is `/tools/pair/<id>`.

![Pair builder: the markets of the chosen asset with Long and Short columns.](https://mintcdn.com/develops-6bdfff15/wHoc8ymqHXCxymk7/images/tools/pair-builder-en-dark.png?fit=max\&auto=format\&n=wHoc8ymqHXCxymk7\&q=85\&s=a1a9eeb0f78ca9892df271a436c6f0df)

Pair builder: the markets of the chosen asset with Long and Short columns.

## Steps

1. Pick an asset in the list on the left, search by ticker or name.
2. In the markets table tick one market in the **Long** column and one in the **Short** column. Use **Market type** to narrow the list.
3. Click **Open spread**.

## Rules

The same rules as in the scanner apply, and the page explains a refused choice:

| Message | Rule |
| - | - |
| **Pick two different markets** | The same market cannot be both legs. |
| **Spot can be the long leg only (or spot vs spot)** | A spot market cannot be shorted. Spot against spot is allowed on two different exchanges. |
| **Margin can be the short leg only** | A margin market is a borrowed coin sold on spot. |
| **Both legs on one exchange are not an arbitrage** | Two markets of one exchange with the same quote do not make a pair. |

The resulting address follows the [spread link grammar](https://docs.spreader.sh/en/links/spread.md), so you can also type it by hand.


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