I built a tool to diff video, image, audio, subtitles and text files — all in one place

The problem

Every time I needed to compare two video renders, two exported images,
or two subtitle files — I ended up with three different tools open,
none of them showing me exactly what changed.

So I built DiffALL.

What it does

Drop any two files. It picks the right engine automatically and gives
you a structured diff in seconds.

Video

• Frame-by-frame SSIM & PSNR scoring
• Synchronized 3-panel live player (expected / heatmap / actual)
• Bounding boxes around every changed region
• Per-second similarity graph — catches transient drops a single score would miss
• Worst-moment timestamp so you jump straight to the bug Images
• Pixel-level difference heatmap
• Standard mode: Expected | Difference | Actual side by side
• Flexible mode: ORB feature matching + homography alignment for photos taken at different angles or lighting

Audio

• MFCC spectral similarity (50% weight)
• Spectral centroid + RMS energy
• Mel spectrogram diff overlay
• Browser playback of both files for manual listening

Subtitles (SRT / VTT)

• Word Error Rate (WER)
• Line-by-line diff with insertions and deletions highlighted
• Timing drift analysis — average, max, and std dev of ms offsets

Text / JSON / CSV / XML / YAML

• Semantic line diff with inline character-level highlighting
• JSON mode: recursive flatten into dotted paths, then structural diff

Tech stack

• Python / Flask on Render free tier
• OpenCV + scikit-image for image and video analysis
• librosa for audio (MFCC, spectral centroid)
• difflib SequenceMatcher for text
• Chart.js for the SSIM timeline
• Supabase for auth

Try it

diffall.onrender.com

Free — no sign-up needed for the first comparison.

Would love feedback on what's missing or broken.