Free KDP coloring-book interior checker
Turn any coloring pages into a KDP-accepted interior PDF
Did Amazon KDP (Kindle Direct Publishing) reject your interior, or do pages print faint? The usual causes are wrong trim, missing margins, under-300-DPI, and bleed set up wrong. Drop your book in for a free per-page check that tells you exactly which — then fix it in one click: every page fit to your KDP trim with safe margins, lines forced to bold pure-black, all combined into one upload-ready PDF at 300 DPI — no-bleed or full-bleed. 100% in your browser — nothing is uploaded.
Independent tool — not affiliated with or endorsed by Amazon / Kindle Direct Publishing (KDP).
↑ A real, untouched sample run through this tool — no upload needed. Drop your own pages below.
Free KDP interior check
Make it print-ready applied to every page
Advanced
Higher catches fainter lines (darkens more); lower only affects the darkest lines. Raise it if faint lines look broken; lower it if the page picks up smudges.
Trim, 300 DPI and KDP-safe margins are applied to every page automatically — pick no-bleed or full-bleed above.
Export your whole book as a KDP-accepted interior PDF
| What you get | Free | Pro · $12 once |
|---|---|---|
| Per-page KDP check — trim · margins · DPI · faint lines | ✓ | ✓ |
| On-screen before / after preview | ✓ | ✓ |
| Export the interior PDF | watermarked | watermark-free |
| 300 DPI · no-bleed / full-bleed · safe margins | — | ✓ |
| True grayscale (DeviceGray) export | — | ✓ |
| Unlimited books & pages, forever | — | ✓ |
Run the full check and see every fixed page on screen for free — pay the one-time $12 only when you’re ready to export. No account, no subscription.
- One upload-ready interior PDF — every page fit to your KDP trim with KDP-safe margins (binding gutter auto-sized to your page count), exported at 300 DPI, no-bleed or full-bleed — your choice. Paid exports are true grayscale (DeviceGray).
- Your whole book in one file — drag in 5 pages or 95; they’re combined in order, ready to upload.
- Crisp, solid-black lines at 300 DPI — faint or gray strokes are darkened to clean solid black while keeping every line’s original weight and detail (nothing thinned or dropped), and scanner speckle is cleaned automatically, so the under-300-DPI rejection can’t happen.
- Runs offline · no subscription · no account · your images never leave your device.
$12 once — not a monthly subscription. Covers the 3 most common interior rejections (wrong trim, missing margins, under-300 DPI) plus bold-black lines — you still create your cover and embed any fonts.
The free version exports a watermarked preview PDF — the diagnosis and on-screen before/after stay free. The $12 key removes the watermark on this device, forever.
How it works
Three steps, about a minute
Drop your pages
Select every interior page (PNG or JPG). They’re read locally in your browser — nothing is uploaded to any server.
See the free check
Every page is scored for resolution and faint lines, with an on-screen before/after preview of the print-ready fix.
Export one PDF
Get a single 300-DPI interior PDF — no-bleed or full-bleed, every page fit to your trim with KDP-safe margins and bold black lines.
FAQ
What KDP self-publishers ask
Why did KDP reject my interior?
The three most common reasons for a coloring-book interior are wrong trim size, no margins / content too close to the edge, and images below 300 DPI. Prepressly fixes all three: it refits every page to the exact KDP trim you pick, insets content to a KDP-safe margin, and rasterizes at a true 300 DPI.
Is the KDP interior checker free?
Yes. The per-page check — page count, binding gutter, resolution (DPI) and faint/gray lines — and the on-screen before/after preview are completely free, with no signup and no upload. You only pay the one-time $12 if you want to export the finished, watermark-free interior PDF.
Will my files be uploaded anywhere?
No. Everything runs in your browser using JavaScript — your images are read and processed on your own device and never sent to a server. You can even disconnect from the internet after the page loads and it still works.
No-bleed or full-bleed?
Both — you choose on export. No-bleed (default) sizes each page to the exact trim with KDP-safe white margins — right for standard line-art coloring pages. Full-bleed enlarges the page to KDP’s exact bleed spec (trim + 0.125″ wide, + 0.25″ tall) and fills the art edge-to-edge — for mandala, pattern and zentangle books designed to print to the edge. Either way there’s no bleed math for you to get wrong.
Does it embed fonts or make a cover?
No — and it doesn’t need to. Pages are exported as images, so there are no fonts to embed (a common source of KDP errors). You still design and upload your cover separately.
What does the $12 unlock?
The free version gives you the full per-page check, the on-screen before/after, and a watermarked preview PDF. The one-time $12 lifetime license removes the watermark so you can export unlimited books and pages, forever — no subscription.
What page sizes are supported?
The most common KDP coloring-book trims: 8.5×11, 8×10, 8.5×8.5, 8.25×8.25, 7×10, and 6×9 inches. Every page is fit to the trim you choose.
Try before you pay. The check and the on-screen before/after are free, so you can confirm Prepressly fixes your exact pages before spending anything. If a paid export ever fails to produce a valid KDP interior PDF, email for a full refund.