---
title: Loading Data | Developer Documentation
description: Loading data using Readers into Documents
---

Before you can start indexing your documents, you need to load them into memory. A reader is a module that loads data from a file into a `Document` object.

To install readers call:

Install @llamaindex/readers

If you want to use the reader module, you need to install `@llamaindex/readers`

```
npm i @llamaindex/readers
```

We offer readers for different file formats.

```
import { CSVReader } from '@llamaindex/readers/csv';
import { DocxReader } from '@llamaindex/readers/docx';
import { HTMLReader } from '@llamaindex/readers/html';
import { ImageReader } from '@llamaindex/readers/image';
import { JSONReader } from '@llamaindex/readers/json';
import { MarkdownReader } from '@llamaindex/readers/markdown';
import { ObsidianReader } from '@llamaindex/readers/obsidian';
import { PDFReader } from '@llamaindex/readers/pdf';
import { TextFileReader } from '@llamaindex/readers/text';
```

## SimpleDirectoryReader

[Open in StackBlitz](https://stackblitz.com/github/run-llama/LlamaIndexTS/tree/main/examples/readers?file=src/simple-directory-reader.ts\&title=Simple%20Directory%20Reader)

LlamaIndex.TS supports easy loading of files from folders using the `SimpleDirectoryReader` class.

It is a simple reader that reads all files from a directory and its subdirectories and delegates the actual reading to the reader specified in the `fileExtToReader` map.

../../examples/readers/src/simple-directory-reader.ts

Currently, the following readers are mapped to specific file types:

- [TextFileReader](/typescript/framework-api-reference/classes/textfilereader/index.md): `.txt`
- [PDFReader](/typescript/framework-api-reference/classes/pdfreader/index.md): `.pdf`
- [CSVReader](/typescript/framework-api-reference/classes/csvreader/index.md): `.csv`
- [MarkdownReader](/typescript/framework-api-reference/classes/markdownreader/index.md): `.md`
- [DocxReader](/typescript/framework-api-reference/classes/docxreader/index.md): `.docx`
- [HTMLReader](/typescript/framework-api-reference/classes/htmlreader/index.md): `.htm`, `.html`
- [ImageReader](/typescript/framework-api-reference/classes/imagereader/index.md): `.jpg`, `.jpeg`, `.png`, `.gif`

You can modify the reader three different ways:

- `overrideReader` overrides the reader for all file types, including unsupported ones.
- `fileExtToReader` maps a reader to a specific file type. Can override reader for existing file types or add support for new file types.
- `defaultReader` sets a fallback reader for files with unsupported extensions. By default it is `TextFileReader`.

SimpleDirectoryReader supports up to 9 concurrent requests. Use the `numWorkers` option to set the number of concurrent requests. By default it runs in sequential mode, i.e. set to 1.

### Example

../../examples/readers/src/custom-simple-directory-reader.ts

## Tips when using in non-Node.js environments

When using `@llamaindex/readers` in a non-Node.js environment (such as Vercel Edge, Cloudflare Workers, etc.) Some classes are not exported from top-level entry file.

The reason is that some classes are only compatible with Node.js runtime, (e.g. `PDFReader`) which uses Node.js specific APIs (like `fs`, `child_process`, `crypto`).

If you need any of those classes, you have to import them instead directly through their file path in the package.

As the `PDFReader` is not working with the Edge runtime, here’s how to use the `SimpleDirectoryReader` with the `LlamaParseReader` to load PDFs:

```
import { SimpleDirectoryReader } from "@llamaindex/readers/directory";
import { LlamaParseReader } from "llama-cloud-services";


export const DATA_DIR = "./data";


export async function getDocuments() {
  const reader = new SimpleDirectoryReader();
  // Load PDFs using LlamaParseReader
  return await reader.loadData({
    directoryPath: DATA_DIR,
    fileExtToReader: {
      pdf: new LlamaParseReader({ resultType: "markdown" }),
    },
  });
}
```

> *Note*: Reader classes have to be added explicitly to the `fileExtToReader` map in the Edge version of the `SimpleDirectoryReader`.

You’ll find a complete example with LlamaIndexTS here: <https://github.com/run-llama/create_llama_projects/tree/main/nextjs-edge-llamaparse>

## Load file natively using Node.js Customization Hooks

We have a helper utility to allow you to import a file in Node.js script.

Terminal window

```
node --import @llamaindex/readers/node ./script.js
```

```
import csv from './path/to/data.csv';


const text = csv.getText()
```

## API Reference

- [SimpleDirectoryReader](/typescript/framework-api-reference/classes/simpledirectoryreader/index.md)