An OPF file is the XML package document inside an EPUB. It lists metadata, manifest resources, and the spine that defines reading order. This tool visualizes all three instantly.

Does this viewer upload my data?

No. Parsing happens entirely within your browser session. Files never leave your device, preserving confidentiality for pre-release titles or client material.

Can I export results for audits?

Yes. Use the manifest CSV export to analyze resources in Excel or Google Sheets, and copy the metadata summary for quick documentation or tickets.

Why do I see warnings in diagnostics?

Warnings highlight missing required fields, orphaned spine references, or outdated package versions. Resolve them to ensure EPUB validators and retailers accept your submission.

OPF Viewer Online

Inspect EPUB package files without leaving your browser. Parse metadata, manifest, spine order, and run instant health checks with optional CSV export, JSON snapshots, manifest search, and shareable permalinks for rapid collaboration.

Upload or Drop Your OPF File

Click to choose an OPF file or drop one here

.opf files stay on this device. Nothing is uploaded.

Awaiting file input.

Package Snapshot

No file loaded

Key Metadata

Manifest Inventory

Resources declared in the OPF manifest
ID	Href	Media Type

Reading Order & Guide

Spine Order

Guide References

Smart Diagnostics

About This OPF Viewer

OPF Viewer Online is engineered for eBook publishers, conversion specialists, and digital librarians who need rapid insight into EPUB package files without surrendering data privacy. Every inspection runs locally in your browser, giving you instant visibility into metadata quality, manifest coverage, and reading order health. Inspired by the balance of clarity and warmth found in Kadence designs, the interface is crafted to stay out of the way while making complex package data understandable at a glance.

How to Use

Drag an OPF file into the drop zone or tap to browse and upload from your device. The viewer parses the XML structure client-side, populating metadata, manifest tables, and spine order in real time. Filter the manifest instantly as you type, copy the metadata summary for tickets, export the inventory to CSV for spreadsheet checks, download a JSON snapshot for automated QA, or generate a permalink to share findings with teammates. When you are done, clear the view to prepare the tool for the next project.

Optimization Tips

Strengthen discoverability by providing at least one title, creator, language, identifier, subject, and description entry within the metadata block. Confirm that every manifest resource referenced in the spine has a matching media type and that navigation files use the correct XHTML or NCX formats. If you include cover art, flag it with the appropriate meta tag attribute so distribution platforms can surface it confidently. Regularly export the manifest to CSV for bulk audits, log JSON snapshots alongside commits, and keep version control notes using the permalink snapshot feature.

FAQs

What is an OPF file?: An OPF file is the XML package document inside an EPUB. It lists metadata, manifest resources, and the spine that defines reading order. This tool visualizes all three instantly.
Does this viewer upload my data?: No. Parsing happens entirely within your browser session. Files never leave your device, preserving confidentiality for pre-release titles or client material.
Can I export results for audits?: Yes. Use the manifest CSV export to analyze resources in Excel or Google Sheets, and copy the metadata summary for quick documentation or tickets.
Why do I see warnings in diagnostics?: Warnings highlight missing required fields, orphaned spine references, or outdated package versions. Resolve them to ensure EPUB validators and retailers accept your submission.

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