⌘ K
png · chunks · forensics · local

Inspect every PNG chunk in a file

Decompose any PNG into IHDR, IDAT, tEXt, iTXt, and ancillary chunks. See length, offset, CRC, and decoded text. Local, no upload.

PNG Chunk Inspector
File
—
no file
Chunks
—
parsed
Critical
—
uppercase
Status
idle
live
input · image

image/png · runs locally · nothing uploaded

output · preview
Chunk list appears here
Quick Start

How it works

Pick an image, tune the options, then download the result. Everything runs in your browser.

  1. 01

    Pick a PNG

    Drop or select any .png file. Parsing runs locally.

    Files stay in memory as an HTMLImageElement — the original bytes are never uploaded, and EXIF metadata is preserved until you explicitly transform it.

    uploadcanvaslocaldecode
    input · bytespng · loaded
    image.png
    loaded · decodedcanvas · ready
  2. 02

    Parse chunk stream

    The PNG signature is verified, then chunks are walked end-to-end.

    Encoder quality is exposed where the format supports it — JPEG and WebP get a 0–1 quality slider; PNG is lossless. Options re-render the canvas immediately.

    parseoptionslive previewencoderquality
    scan · tunablechunks · live
    IHDR -> [tEXt, iTXt, ...] -> IDAT -> IEND
    options applied · liveencoder · live
  3. 03

    Decode metadata

    Text chunks (tEXt/iTXt/zTXt) are decoded inline so you can read embedded metadata.

    Pixel work runs on the Canvas 2D context — drawImage resamples with the browser’s bilinear filter and getImageData/putImageData back per-pixel passes.

    textrenderCanvas 2Dpreviewpx-perfect
    text · resampleddecoded · px-perfect
    tEXt: "Software": "Photoshop"
    preview · livepx-perfect
  4. 04

    Copy table

    Grab the type/length/offset/CRC list for your bug report.

    Downloads ship via a hidden anchor with an object URL — no server round-trip, and the file on disk is untouched. The output filename inherits a sensible suffix.

    exportdownloadblobclient-sideobject URL
    ok · blobready · saved
    table copied
    shipped · ready to shipsuccess
Pro tips

Browser-only image work that scales

Convert with quality control

JPEG/WebP let you pick a 0–1 quality. Default 0.92 is a good compromise of size and visible quality.

PNG isn’t free

Use PNG only for transparency or sharp edges. For photos, WebP is smaller at the same perceived quality.

Strip EXIF for privacy

Photo EXIF often contains GPS, camera model, and timestamps. Strip before sharing public uploads.

Watch the colour profile

Convert to sRGB before web export. Wide-gamut images render oversaturated in non-managed browsers.

AVIF when it’s available

AVIF beats WebP on size at the same quality. Detect support via <picture> with fallbacks.

Lazy-load below the fold

Add loading="lazy" on <img>. The browser handles scheduling — no IntersectionObserver needed.

Related toolsEXIF ViewerBulk StripperHex ViewerPNG QuantizerEXIF StripperDimension Inspector
Use Cases

When to use this tool

Common workflows it speeds up.

Metadata audits

Spot embedded EXIF or comments before publishing. Decoded into a Canvas 2D context — original bytes never leave the tab, so you can process customer-uploaded photos, internal screenshots, or sensitive diagrams without privacy concerns.

px-perfect

File forensics

Verify a file matches the PNG spec strictly. Encoders expose quality 0–1 where the format supports it (JPEG, WebP); PNG and AVIF stay perceptually lossless. Pick 0.85 for web, 0.95 for archival, 0.7 for thumbnails.

quality-tunable

Tool debugging

Inspect output from PNG encoders. Pair with the EXIF Stripper before sharing user-uploaded photos publicly. Camera serial numbers, GPS coordinates, and timestamps often hide in image metadata and leak more than the picture itself.

format-aware

APNG diagnostics

Spot acTL/fcTL/fdAT animation chunks. Output preserves colour profile (sRGB) so it renders consistently across browsers, monitors, and print pipelines. Wide-gamut workflows can opt into Display P3 for modern Apple devices.

EXIF-safe

CRC validation

Compare checksums against expected values. Re-runs only on option changes, never on window resize, so the canvas stays responsive on large images. drawImage uses the browser's bilinear filter for fast resampling.

client-side

Spec learning

Hands-on PNG format walkthroughs. Downloads as .png, .jpg, .webp, or .avif with the correct MIME so editors apply native handling on save. The filename inherits a sensible suffix derived from the input.

compression-ready
FAQ

Frequently asked questions

Critical chunks (uppercase first letter, like IHDR, IDAT, IEND, PLTE) are required for decoding. Ancillary chunks carry optional metadata.
zTXt chunks contain zlib-compressed text. The decoder shows the keyword but skips decompression.
No — it's read-only inspection.
Animation chunks (acTL, fcTL, fdAT) are recognised and labelled.
No. Parsing runs locally in your browser.
Suggest a tool

Something missing?

Tell us what you need. We ship the top requests every two weeks.

Sent straight to the maintainers · no account needed
47 in queue·8 shipped this month
Request queued. Thanks!