Free OCR API: How to Build Text Extraction into Your App

OCR API Options for Developers

There are three main categories of OCR APIs: cloud services (paid per use), self-hosted open source (free but requires infrastructure), and free-tier online tools (limited but zero cost).

Pricing Comparison

Code Examples

Most OCR APIs follow the same shape: you hand over a file, then read back the text. FastOCR uploads straight to storage with a short-lived URL, so large PDFs never pass through the API itself.

Python — Using requests

import os, uuid, requests

BASE = "https://api.fastocr.org"
headers = {"Authorization": f"Bearer {os.environ['FASTOCR_KEY']}"}

# 1. Create the job
job = requests.post(
    f"{BASE}/v1/documents",
    headers={**headers, "Idempotency-Key": str(uuid.uuid4())},
    json={"filename": "receipt.pdf", "size_bytes": os.path.getsize("receipt.pdf")},
).json()

# 2. Upload the file to the presigned URL
with open("receipt.pdf", "rb") as f:
    requests.put(job["upload_url"], data=f,
                 headers={"Content-Type": "application/pdf"})

# 3. Start processing, then poll until it finishes
requests.post(f"{BASE}/v1/documents/{job['id']}/start", headers=headers)

# 4. Download the text once status is "completed"
out = requests.get(f"{BASE}/v1/documents/{job['id']}/output?format=text",
                   headers=headers).json()
print(requests.get(out["url"]).text)

cURL

curl -s -X POST "https://api.fastocr.org/v1/documents" \
  -H "Authorization: Bearer $FASTOCR_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{"filename":"receipt.pdf","size_bytes":12345}'

The full request and response reference — including bank statement extraction to Excel, and what each error code means — lives in the API documentation. The API is currently in private beta.

Self-Hosting Tesseract

Tesseract is the most popular open-source OCR engine. It is free to use and supports over 100 languages. Here is a quick setup:

1. Install Tesseract: apt install tesseract-ocr or brew install tesseract
2. Install language packs: apt install tesseract-ocr-arab tesseract-ocr-hin
3. Run OCR: tesseract input.png output.txt

For production use, wrap Tesseract in an API using Flask, FastAPI, or Express.js. Add image preprocessing (contrast enhancement, deskewing) to improve accuracy significantly.

When to Use Each Option

• Prototyping or personal project — use FastOCR (free, zero setup)
• Production app with < 1K pages/month — Google Cloud Vision free tier
• Production app with > 10K pages/month — Tesseract self-hosted (cheapest at scale)
• Enterprise with compliance needs — Azure or AWS with SLA and encryption
• Multilingual documents — Google Cloud Vision or FastOCR (best language coverage)