Why would a file in my archive have the wrong MIME type?

Files can end up with mismatched types through bulk renaming, format conversion without updating the extension, migration between systems that strip metadata, or simple human error. Content-based detection identifies what the file actually is regardless of its name.

Can I use this report as part of a records management audit?

Yes. The tab-separated output maps each filename to its detected MIME type and can be attached as a format inventory to an archive record. It documents what formats are present in a batch at the time of inspection.

What happens to files that are empty or unrecognizable?

Empty files are explicitly reported as application/x-empty. Files that cannot be identified are reported as application/octet-stream. Every file in the batch appears in the report — nothing is silently dropped.

How many files can I inspect in one batch?

Up to 50 files or 2GB total per batch. For large archives, run multiple batches and combine the reports — the output format is consistent across runs.

MIME Type Detection for Document Archiving and Records Management

Legacy document archives routinely contain files whose extensions no longer reflect their actual format — files converted years ago, batch-renamed incorrectly, or migrated between systems without metadata preservation. Deliteful's File MIME Type Detector identifies the true type of each file using content-based inspection, giving records managers a reliable inventory before migration, audit, or long-term storage.

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Accurate format documentation is a baseline requirement in records management: when files are ingested with incorrect or missing format metadata, downstream consequences include failed format validation, broken rendering in document management systems, and compliance gaps during audits. A batch MIME detection run before ingestion creates a verified format manifest that can be attached to the archive record.

The tool outputs a tab-separated .txt file — filename and detected MIME type, one row per file — that serves directly as a format inventory document. Content-based detection catches discrepancies that extension checking misses: a DOCX file accidentally saved as .doc, a PDF masquerading as .txt, or a zero-byte placeholder logged as application/x-empty rather than silently included in the archive.

How it works

1
Sign in with Google
Create your free Deliteful account in 3 clicks — no credit card required.
2
Upload the archive batch
Upload up to 50 files per run (2GB max) — PDFs, DOCX, XLSX, images, ZIPs, and more are all supported.
3
Download the format inventory
Receive a tab-separated .txt report mapping each filename to its content-detected MIME type for your archive records.

Frequently asked questions

Why would a file in my archive have the wrong MIME type?: Files can end up with mismatched types through bulk renaming, format conversion without updating the extension, migration between systems that strip metadata, or simple human error. Content-based detection identifies what the file actually is regardless of its name.
Can I use this report as part of a records management audit?: Yes. The tab-separated output maps each filename to its detected MIME type and can be attached as a format inventory to an archive record. It documents what formats are present in a batch at the time of inspection.
What happens to files that are empty or unrecognizable?: Empty files are explicitly reported as application/x-empty. Files that cannot be identified are reported as application/octet-stream. Every file in the batch appears in the report — nothing is silently dropped.
How many files can I inspect in one batch?: Up to 50 files or 2GB total per batch. For large archives, run multiple batches and combine the reports — the output format is consistent across runs.

Sign up free with Google and generate a verified MIME type inventory for your document archive before your next migration or audit.