# Page Not Found

The URL `data-retrieval/using-frontend-callback"` does not exist.

You might be looking for one of these pages:
- [Using Frontend Callback](https://docs.impler.io/data-retrieval/using-frontend-callback.md)
- [Using Webhook](https://docs.impler.io/data-retrieval/using-webhook.md)
- [Writing effectively into .xlsm files](https://docs.impler.io/additional-resources/writing-effectively-into-.xlsm-files.md)
- [Freeze Columns](https://docs.impler.io/features/freeze-columns.md)
- [Default Value](https://docs.impler.io/features/default-value.md)

## How to find the correct page

1. **Browse the full index**: [/sitemap.md](https://docs.impler.io/sitemap.md) - Complete documentation index
2. **View the full content**: [/llms-full.txt](https://docs.impler.io/llms-full.txt) - Full content export

## Tips for requesting documentation

- For markdown responses, append `.md` to URLs (e.g., `/data-retrieval/using-frontend-callback.md`)
- Use `Accept: text/markdown` header for content negotiation