Copy for LLM[View as Markdown](https://docs.planet.com/develop/)

# Developer Overview

## Authentication

Planet APIs use different authentication methods depending on the domain (`api.planet.com` or `sentinel-hub.com`). See the [authentication section](https://docs.planet.com/develop/authentication.md) for details.

## Errors

Understand common HTTP and API-specific errors you may encounter when using Planet APIs — and how to resolve them. See the [errors section](https://docs.planet.com/develop/errors.md) for details.

## Rate Limiting

Learn how Planet enforces rate limits, and how to manage 429 errors using strategies like exponential backoff. See the [rate limiting section](https://docs.planet.com/develop/rate-limiting.md) for details.

## SDKs and Developer Resources

Explore official SDKs, CLI tools, and open-source libraries for working with Planet and Sentinel data. See the [SDKs section](https://docs.planet.com/develop/sdks.md) for guides, examples, and frameworks like `eo-learn` and `eo-grow`.

## Evalscripts

Write custom JavaScript scripts to process and visualize satellite data, apply logic, and extract metadata using Planet's Evalscript engine.

### [Functions](https://docs.planet.com/develop/evalscripts/functions.md)

[Evalscript is a powerful tool for imagery visualization, multitemporal scripting, datafusion, scene filtering, and more.](https://docs.planet.com/develop/evalscripts/functions.md)

### [Utilities](https://docs.planet.com/develop/evalscripts/utilities.md)

[Explore the nonstandard javascript visualizers and helper functions, that can be used in your evalscript.](https://docs.planet.com/develop/evalscripts/utilities.md)

### [Examples](https://docs.planet.com/develop/evalscripts/examples.md)

[Explore examples of evalscripts using the Sentinel-2 L2A data collection.](https://docs.planet.com/develop/evalscripts/examples.md)

### [Data Fusion](https://docs.planet.com/develop/evalscripts/data-fusion.md)

[Combine multiple data sources — different collections, or the same collection at different dates — in a single evalscript request.](https://docs.planet.com/develop/evalscripts/data-fusion.md)