File Conversion API

A free, open source REST API for file conversion. Convert between image formats, resize, compress, extract text from PDFs, and more — all in memory, nothing stored on disk.

✓ Free & Open Source ✓ No API Key Required ✓ Files Never Stored Self-Hostable MIT License

Overview

All operations happen entirely in memory. Files are processed and returned immediately — no temporary files are written to disk, and nothing is retained after the response is sent.

Supported Image Formats

PNG

JPG

WebP

GIF

BMP

TIFF

PDF Operations

Operation	Description	Output
Text extraction	Extract raw text from all pages	JSON
Page to images	Render each page as an image	ZIP file
Metadata	Page count, author, dimensions, encryption	JSON

Base URL

https://file-conversion-api-xnhs.onrender.com

All endpoints accept multipart/form-data. JSON responses use application/json. File responses include a Content-Disposition: attachment header.

Authentication

🔓 No authentication required. All endpoints are publicly accessible. CORS is enabled for all origins.

File Limits

Constraint	Value
Max file size	20 MB per request
Max image dimension (resize)	10,000 × 10,000 px
PDF to images DPI	72 – 300 DPI
Quality range (JPG/WebP)	1 – 100

⚠️ Converting a large PDF to images at 300 DPI is memory-intensive. For files over 10MB, use 150 DPI or lower.

Rate Limiting

Endpoint	Limit
Image endpoints	30 requests / minute per IP
PDF text / info	30 requests / minute per IP
PDF to images	10 requests / minute per IP

Exceeded limits return HTTP 429 with a Retry-After header.

Image Endpoints

POST /convert/image Convert image to another format

Form Fields

Field	Type	Required	Default	Description
`file`	File	required	—	Input image file.
`format`	string	optional	`png`	Output format: `png`, `jpg`, `webp`, `gif`, `bmp`, `tiff`.
`quality`	integer	optional	`85`	Compression quality 1–100 (applies to JPG and WebP only).

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/image \
  -F "file=@photo.png" \
  -F "format=webp" \
  -F "quality=80" \
  --output converted.webp

Returns the converted image file with appropriate Content-Type and Content-Disposition headers.

POST /convert/image/resize Resize an image to specific dimensions

Form Fields

Field	Type	Required	Default	Description
`file`	File	required	—	Input image.
`width`	integer	required	—	Target width in pixels.
`height`	integer	required	—	Target height in pixels.
`keep_aspect`	boolean	optional	`true`	Preserve aspect ratio (thumbnail mode). If false, stretches to exact dimensions.
`format`	string	optional	`png`	Output format.
`quality`	integer	optional	`85`	Quality 1–100 (JPG/WebP only).

Response Headers

Header	Description
`X-Original-Size`	Original dimensions, e.g. `1920x1080`
`X-Output-Size`	Final dimensions after resizing

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/image/resize \
  -F "file=@photo.jpg" \
  -F "width=800" \
  -F "height=600" \
  -F "keep_aspect=true" \
  -F "format=jpg" \
  --output resized.jpg

POST /convert/image/compress Compress an image and report size reduction

Form Fields

Field	Type	Required	Default	Description
`file`	File	required	—	Input image.
`quality`	integer	optional	`60`	Output quality 1–100. Lower = smaller file.
`format`	string	optional	Same as input	Output format (defaults to same as input).

Response Headers

Header	Description
`X-Original-Size-Bytes`	Input file size in bytes
`X-Compressed-Size-Bytes`	Output file size in bytes
`X-Compression-Ratio`	Size reduction, e.g. `42.3%`

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/image/compress \
  -F "file=@photo.jpg" \
  -F "quality=50" \
  --output compressed.jpg -v

PDF Endpoints

POST /convert/pdf/text Extract text content from a PDF

Form Fields

Field	Type	Required	Description
`file`	File	required	Input PDF file.

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/pdf/text \
  -F "file=@document.pdf"

Example Response

{
  "page_count": 3,
  "full_text": "Introduction\n\nThis document describes...",
  "pages": [
    { "page": 1, "text": "Introduction\n\nThis document describes..." },
    { "page": 2, "text": "Chapter 1: Getting Started..." },
    { "page": 3, "text": "" }
  ]
}

💡 Text extraction works only on text-based PDFs. Scanned image PDFs will return empty strings per page — use OCR software for those.

POST /convert/pdf/images Convert each PDF page to an image — returns a ZIP

Form Fields

Field	Type	Required	Default	Description
`file`	File	required	—	Input PDF.
`format`	string	optional	`png`	`png` or `jpg`.
`dpi`	integer	optional	`150`	Render resolution (72–300). Higher = sharper but larger files.

Returns a application/zip file named pdf_pages.zip containing page_1.png, page_2.png, etc.

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/pdf/images \
  -F "file=@document.pdf" \
  -F "format=png" \
  -F "dpi=150" \
  --output pages.zip

⚠️ Requires poppler-utils to be installed on the server. Included in the Render deployment via render.yaml.

POST /convert/pdf/info Extract metadata and page info from a PDF

Form Fields

Field	Type	Required	Description
`file`	File	required	Input PDF.

Example Request

curl -X POST https://file-conversion-api-xnhs.onrender.com/convert/pdf/info \
  -F "file=@document.pdf"

Example Response

{
  "page_count": 5,
  "encrypted": false,
  "file_size_bytes": 204800,
  "metadata": {
    "title": "Annual Report 2025",
    "author": "Jane Doe",
    "subject": null,
    "creator": "Microsoft Word",
    "producer": "Adobe PDF Library",
    "creation_date": "D:20250115120000",
    "modification_date": "D:20250116090000"
  },
  "pages": [
    { "page": 1, "width_pt": 595.28, "height_pt": 841.89 },
    { "page": 2, "width_pt": 595.28, "height_pt": 841.89 }
  ]
}

Utility Endpoints

GET /formats List all supported formats

{
  "image_input": ["png", "jpg", "jpeg", "webp", "gif", "bmp", "tiff"],
  "image_output": ["png", "jpg", "jpeg", "webp", "gif", "bmp", "tiff"],
  "pdf_operations": ["text", "images", "info"]
}

GET /health Health check

{ "status": "ok" }

Error Codes

Code	Meaning	Common Cause
400	Bad Request	Unsupported format, invalid quality/DPI, non-PDF file sent to PDF endpoint, corrupt image.
413	Payload Too Large	File exceeds the 20 MB limit.
429	Too Many Requests	Rate limit exceeded.
501	Not Implemented	`pdf2image` / `poppler` not installed on the server.

Error Response Format

{ "detail": "File exceeds 20MB limit." }

Legal & Privacy

Data Retention

No files are ever stored. All processing happens exclusively in RAM. Once the HTTP response is sent, the data is discarded. There are no logs containing file content, and no backups of processed files.

GDPR Compliance

Because no personal data is persisted, this API does not create data retention obligations. However, integrators are responsible for ensuring they have a lawful basis for processing files that may contain personal data belonging to their own users.

Content Responsibility

Users are solely responsible for the legality and copyright status of files submitted to the API. Do not upload files you do not own or have a license to process. The API may not be used to process unlawful content.

Copyright Notice

Text extraction from a PDF does not grant any rights to the extracted content. Copyright remains with the original author. The API is a technical tool — use it only on content you are authorized to process.

Acceptable Use

Must not be used for bulk automated processing of copyrighted material, malware distribution, or any unlawful purpose. The service reserves the right to block abusive IPs.

License

Source code is released under the MIT License. You are free to self-host, modify, and redistribute.

Self-Hosting

Dependencies

pdf2image (used by POST /convert/pdf/images) requires poppler:

# Ubuntu / Debian
apt-get install -y poppler-utils

# macOS
brew install poppler

Run locally

git clone https://github.com/your-username/file-conversion-api
cd file-conversion-api
pip install -r requirements.txt
uvicorn main:app --reload

Interactive docs at http://localhost:8000/docs

Deploy on Render

The render.yaml automatically installs poppler-utils as a build step. Connect your GitHub repo and Render handles the rest.