Why TinyPNG rejects your file
TinyPNG is a popular PNG and JPEG compressor. It works well for web developers compressing small graphics. The constraint is its free-tier upload cap: 5 MB per file, 20 files per session. Any photo from a modern phone — typically 3–8 MB for JPEG, 4–12 MB for RAW or HEIC — often hits the limit.
The 5 MB cap exists because TinyPNG's business model is server-side processing. Every file you submit is uploaded, compressed on their infrastructure, and sent back. Larger files cost them more to process, so the free tier is gated.
What LocalJPG does differently
LocalJPG runs the conversion inside your browser using WebAssembly — the same technology that powers browser-based games and code editors. There is no server involved, so there is no upload size limit to enforce. A 30 MB HEIC panorama processes exactly the same as a 1 MB snapshot.
The output is JPEG rather than PNG. If your goal is the smallest file for sharing, email, or social media, JPEG is the right format — it achieves smaller sizes than PNG for photographic content while keeping quality indistinguishable from the original at quality 85. EXIF metadata (date, GPS, camera model) is preserved through the conversion.
When TinyPNG is still the right choice
TinyPNG keeps files in PNG format, which preserves transparency. If you are compressing logos, UI assets, or images with transparent backgrounds for a website, TinyPNG is better suited — JPEG does not support transparency, so LocalJPG would flatten the transparent areas to white.
For photos — iPhone shots, scanned documents, product photos — LocalJPG handles the job with no size limit and no upload.
Related: LocalJPG vs TinyPNG · HEIC to JPG · Convert HEIC without uploading