---
title: Read and write OWLF
description: Validate OWLF files and convert app exports in the browser, in React Native or in Node.
---

```bash
npm install @owlf/core @owlf/adapters
```

## Convert an export

```ts
import { detectAdapters } from "@owlf/adapters";
import { fileFromBlob, stringifyDocument } from "@owlf/core";

const files = [fileFromBlob(droppedFile)]; // a browser File
const [best] = await detectAdapters(files); // [{ adapter, score }], best first
const document = await best.adapter.parse(files);

const text = stringifyDocument(document); // data.owlf.json
```

Need one app only? Install its package, e.g. `@owlf/adapter-daylio`, and call `daylio.parse(files)`.

## Validate a file

```ts
import { parseDocument, validateDocument } from "@owlf/core";

const result = validateDocument(JSON.parse(text));
if (!result.ok) {
  console.log(result.issues); // [{ path: "entries.3.mood.level", message: "Unknown level \"x\"" }]
}

const document = parseDocument(text); // throws with the first issues when invalid
```

`validateDocument` checks the schema plus what JSON Schema cannot: level references, real calendar dates, `zoneless` only with an `instant`.

## Runtimes

- **Browser and React Native**: every package's main entry. No Node APIs, no network requests.
- **Node 22+**: ESM and `require()`.
- **`@owlf/core/testkit`**: Node and Bun only, it reads fixtures from disk.