Matthew Jackson
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Reverse geocodes GPS coords via Nominatim to show the real location that was embedded in the photo, making it clear what was stripped. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
PostConvert – Robust Image & PDF → JPEG Conversion Service
PostConvert is a small, production-oriented HTTP service for converting images and PDFs into JPEGs, with strong emphasis on robustness, predictable resource usage, and operational safety.
It supports:
- JPEG → JPEG (resize + recompress)
- PNG / WebP / TIFF → JPEG
- HEIC / HEIF → JPEG (via WASM fallback)
- PDF → JPEG (first page or all pages as a ZIP)
The service is designed to run well in containers, serverless-ish environments, and small VMs where disk, memory, and runaway workloads matter.
Primary Use Cases
- Normalize user uploads (receipts, photos, scans) into JPEG
- Resize and recompress images server-side for storage or ML pipelines
- Convert PDFs (receipts, invoices, statements) into images
- Handle HEIC uploads from iOS devices without native libheif dependencies
- Safely process untrusted user uploads with bounded resource usage
Key Design Goals
- Always JPEG out
- Bounded
/tmpusage (PDFs rendered page-by-page) - No stack traces leaked to clients
- Fast path for common formats
- Graceful abort on client disconnect
- Predictable limits (size, pages, DPI, timeouts)
Endpoints
POST /convert
Converts a single image or the first page of a PDF to a JPEG.
Supported inputs
- JPEG, PNG, WebP, TIFF, etc. (anything Sharp can decode)
- HEIC / HEIF
- PDF (first page only)
Response
200 image/jpegon success- JSON error on failure
POST /convert/pdf
Converts all pages of a PDF into JPEGs and returns a ZIP archive.
Pages are rendered one at a time to keep disk usage bounded.
Authentication
All endpoints require a bearer token.
Authorization: Bearer <CONVERTER_TOKEN>
Image Resize & JPEG Options (Headers)
| Header | Type | Default | Description |
|---|---|---|---|
x-jpeg-quality |
0–100 |
100 |
JPEG compression quality |
x-max-dimension |
px | none | Max width/height, aspect preserved |
x-width |
px | none | Explicit output width |
x-height |
px | none | Explicit output height |
x-fit |
enum | inside |
inside, cover, contain, fill, outside |
x-without-enlargement |
bool | true |
Prevent upscaling smaller images |
Environment Variables
| Variable | Default | Description |
|---|---|---|
PORT |
8080 |
Server port |
CONVERTER_TOKEN |
(required) | Bearer auth token |
Runtime Dependencies
- Node.js 18+
pdftoppm(Poppler utils) required for PDFs- Sharp native dependencies (per Sharp docs)