# Start Here

KyberSwap provides three APIs for building on-chain trading and liquidity features - the [Aggregator API](/developer-guide/aggregator-api.md) for instant token swaps, the [Zap as a Service (ZaaS) API](/developer-guide/zap-as-a-service-zaas-api.md) for streamlined liquidity provision, and the [Limit Order API](/developer-guide/limit-order-api.md) for gasless and price-conditional trades. This section covers everything that applies across all three: how to choose the right API, usage limits, supported chains, and the core solutions behind how they work.

## Which API Should I Use?

KyberSwap offers 3 APIs. Find your use case in the table below.

<table><thead><tr><th width="492.3203125">I want to...</th><th>Use this</th></tr></thead><tbody><tr><td>Swap token A → token B at the best available rate</td><td><a href="/pages/dY9bu639SydnIk0eHS1M">Aggregator API</a></td></tr><tr><td>Swap token A → token B at a price I set</td><td><a href="/pages/IfTxo5r5SbCVuJgc4J8i">Limit Order API</a></td></tr><tr><td>Add liquidity to a supported pool using any token</td><td><a href="/pages/0e8e4bKtsVL76xoN4Lhv">Zap as a Service API</a></td></tr><tr><td>Remove liquidity and receive a single token</td><td><a href="/pages/0e8e4bKtsVL76xoN4Lhv">Zap as a Service API</a></td></tr><tr><td>Migrate from a position to a new position</td><td><a href="/pages/0e8e4bKtsVL76xoN4Lhv">Zap as a Service API</a></td></tr><tr><td>Fill open limit orders as a taker or arbitrage bot</td><td><a href="/pages/IfTxo5r5SbCVuJgc4J8i">Limit Order API</a></td></tr></tbody></table>

* [**KyberSwap Aggregator** **API**:](/developer-guide/aggregator-api.md) Provides developers with more fine-tuned control when integrating swap functionality within their app. We provide guidelines and code samples on how to query and execute swaps at the favourable rates.
  * [**KyberSwap Widget**](/developer-guide/aggregator-api/how-to-guides/kyberswap-widget.md): Plug and play superior rates directly from your app with just a few lines of code. Our [endlessly customizable widget](https://app.gitbook.com/o/2RCW3YGZHRsvcw6VtGeF/s/w1XgQJc40kVeGUIxgI7c/kyberswap-solutions/kyberswap-widget/developer-guides/customizing-the-kyberswap-widget) enables integrators to seamlessly blend superior rates into their dApps with easily configurable trade routes, fees, and themes.
* [**Limit Order API:**](https://docs.kyberswap.com/kyberswap-solutions/limit-order/developer-guides) A set of [Maker](/developer-guide/limit-order-api.md#maker) and [Taker](/developer-guide/limit-order-api.md#taker) APIs enables gasless management of limit orders secured by the option to settle on-chain. When settling orders on-chain, KyberSwap Limit Order provides the relevant APIs required to encode the call data to be sent to the Limit Order smart contracts.
* [**KyberSwap Zap as a Service (ZaaS)**](/developer-guide/zap-as-a-service-zaas-api.md): An API that streamlines decentralized liquidity provision. Powered by [KyberSwap Aggregator](/developer-guide/aggregator-api.md), Zap minimizes price impact and employs fallback logic to execute additional swaps when necessary - maximizing capital efficiency and reducing failure rates, even during volatile market conditions.

## Rate Limits & Client ID

KyberSwap APIs do not require authentication. Include `x-client-id` header in every request, using your app or company name as the value. Refer to [Rate Limits & Client ID](/developer-guide/start-here/rate-limits-and-client-id.md) for further details.

## Supported Chains & Networks

All KyberSwap APIs are EVM-only. Each API is available on a different subset of chains. See [Supported Chains & Networks](/getting-started/supported-exchanges-and-networks.md) for the full list, including the chain identifier strings required in API paths.

## Foundational Solutions

A short set of solutions that explain why the APIs are designed the way they are - covering trade routing, off-chain relay, and gasless approvals. If you're new to KyberSwap's architecture, read these before integrating. See [Foundational Solutions](/developer-guide/start-here/foundational-solutions.md).


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