# Summarize PDFs with JavaScript & Node.js — API Tutorial

Call the PDF Summarizer API from Node.js (or any server-side JavaScript runtime) with nothing more than fetch and FormData. This tutorial covers a first request, streaming, a small Express endpoint for your own app, and error handling.

## Key facts

- Works with Node.js 18+ (built-in fetch, FormData, Blob) — no SDK needed.
- POST https://pdf-summarize.com/api/summarize.php, multipart/form-data, field file, header Authorization: Bearer sk_....
- Options: length, format, outputLang, includeKeywords.
- Add ?stream=1 and read the response body as Server-Sent Events.
- Never expose your key in browser code — proxy requests through your server.

## Your first request in Node.js

1. **Get a free API key** — Sign up and copy it from your dashboard.
2. **Store it in an environment variable** — PDF_SUMMARIZE_KEY.
3. **Build a FormData** — Append the PDF as a Blob under the field file.
4. **POST it and read the JSON.** — 

```js
// summarize.mjs — node summarize.mjs report.pdf
import { readFile } from 'node:fs/promises';
import { basename } from 'node:path';

const API_URL = 'https://pdf-summarize.com/api/summarize.php';
const KEY = process.env.PDF_SUMMARIZE_KEY;

export async function summarizePdf(path, { length = 'medium', format = 'bullets', outputLang = 'auto' } = {}) {
  const form = new FormData();
  form.append('file', new Blob([await readFile(path)], { type: 'application/pdf' }), basename(path));
  form.append('length', length);
  form.append('format', format);
  form.append('outputLang', outputLang);

  const res = await fetch(API_URL, {
    method: 'POST',
    headers: { Authorization: `Bearer ${KEY}` },
    body: form,
    signal: AbortSignal.timeout(180_000),
  });
  const data = await res.json();
  if (!res.ok || !data.success) throw new Error(`${res.status}: ${data.error ?? JSON.stringify(data)}`);
  return data;
}

const result = await summarizePdf(process.argv[2]);
console.log(result.summary);
console.log(`${result.page_count} pages, ${result.processing_time}s, ${result.requests_remaining} requests left`);
```

## Streaming the summary

```js
export async function streamSummary(path, onText) {
  const form = new FormData();
  form.append('file', new Blob([await readFile(path)], { type: 'application/pdf' }), basename(path));
  form.append('length', 'long');

  const res = await fetch(API_URL + '?stream=1', { method: 'POST', headers: { Authorization: `Bearer ${KEY}` }, body: form });
  if (!res.ok) throw new Error(`HTTP ${res.status}`);

  const decoder = new TextDecoder();
  let buffer = '';
  for await (const chunk of res.body) {
    buffer += decoder.decode(chunk, { stream: true });
    const lines = buffer.split('\n');
    buffer = lines.pop();
    for (const line of lines) {
      if (!line.startsWith('data: ')) continue;
      const payload = line.slice(6);
      if (payload === '[DONE]') return;
      const event = JSON.parse(payload);
      if (event.error) throw new Error(event.error);
      if (event.type === 'summary') onText(event.content);
    }
  }
}

await streamSummary('paper.pdf', (t) => process.stdout.write(t));
```

## An Express endpoint for your own app

Your front-end uploads to **your** server, which adds the key and forwards the file:

```js
import express from 'express';
import multer from 'multer';

const app = express();
const upload = multer({ limits: { fileSize: 20 * 1024 * 1024 } });

app.post('/summarize', upload.single('file'), async (req, res) => {
  if (!req.file) return res.status(400).json({ error: 'No file' });
  const form = new FormData();
  form.append('file', new Blob([req.file.buffer], { type: 'application/pdf' }), req.file.originalname);
  form.append('length', req.body.length ?? 'medium');
  const r = await fetch('https://pdf-summarize.com/api/summarize.php', {
    method: 'POST', headers: { Authorization: `Bearer ${process.env.PDF_SUMMARIZE_KEY}` }, body: form,
  });
  res.status(r.status).json(await r.json());
});

app.listen(3000);
```

## Error handling

| Status | Meaning |
|---|---|
| 400 | Missing file, not a PDF, or page limit exceeded |
| 401 | Missing or invalid key |
| 413 | File too large |
| 422 | No readable text in the PDF |
| 429 | Rate limit or quota reached — retry later with backoff |
| 500 | Temporary summarization error — retry |

> **See the engine in action first** — Try the free web tool with one of your PDFs.

## FAQ

### Can I call the API directly from the browser?

Technically yes, but your key would be visible to anyone. Proxy requests through your backend as in the Express example.

### Does it work with Deno, Bun or Cloudflare Workers?

Yes — any runtime with standard fetch and FormData works the same way.

### Is there a TypeScript SDK?

Not yet. The API is a single multipart endpoint, so a small typed wrapper around fetch is enough.

### Where is the full reference?

In the API documentation, with all parameters and examples in several languages.

---
Source: https://pdf-summarize.com/guides/pdf-summary-api-javascript — PDF Summarizer (free PDF summarizer, Q&A with page citations, OCR, REST API). Site overview: https://pdf-summarize.com/llms.txt