LanFutureInspect the evidence.
Choose a finding to inspect its origin, location and next step.
Free interactive walkthrough / recorded synthetic data
An EPUB error.
A clearer next step.
Explore actual findings from a synthetic EPUB checked locally by Book Preflight Studio and EPUBCheck 5.3.0. See the difference between a narrow container repair and an issue that needs your editor.
This page explores a recorded example. It does not accept files, run EPUBCheck, repair a book or certify accessibility.
Enable JavaScript to explore the recorded report, or open the static report below.
Three repairs, not a universal fixer
Container details are one thing.
Your book is another.
The desktop app can propose repairs to the existing mimetype marker: order in the ZIP, uncompressed/no-extra-field storage and proven marker-byte normalization. Approved desktop exports revalidate the original and proposed snapshots. Existing unrelated findings can remain.
Broken content links, editorial changes, rendering and accessibility may need separate tools and qualified manual review. EPUBCheck and Ace are independently available alternatives. Read the W3C EPUB container rules.
Need the complete workflow?
Book Preflight Studio
Independent authors, small publishers and production freelancers with a supported EPUB ready for structural review. The desktop workflow adds projects, evidence, human review decisions, reports and backups for your own supported files.
Technical privacy overview
Your work stays local.
AI is a separate choice.
The desktop apps store snapshots, projects and review history locally. Core checks do not require cloud AI. License activation/validation contacts the licensing service when used. Optional AI sends the exact request you preview and approve; the API provider's policies apply.
Product-information pages use no executable JavaScript. The separate free preview tools use only first-party browser code, with no analytics, cookies, storage or network submission. Text in the placeholder checker stays in page memory until cleared or closed. Host request metadata and emails you choose to send may still be processed. This overview is not a finalized sales policy.