How should I use MIME type detection in a data migration workflow?

Run MIME detection on each batch before migration. Compare the detected types against the expected types from your source system manifest. Files flagged as application/octet-stream or with mismatched types should be reviewed before being migrated to the target system.

What file types are supported for MIME detection?

Supported types include PDF, XLSX, XLS, CSV, DOCX, TXT, PNG, JPG, JPEG, WEBP, ZIP, JSON, TAR, TGZ, and TAR.GZ. Each file can be up to 50MB; batches support up to 50 files or 2GB total.

Will the tool modify my files during detection?

No. MIME detection is a read-only operation. Your uploaded files are inspected but never modified. Only the detection report is returned as output.

What does application/octet-stream mean in the context of migration?

application/octet-stream means the tool could not match the file to a known format. In a migration context, this is a signal to manually review the file before migrating it — it may be corrupted, an unsupported format, or a file type the target system cannot handle.

Pre-Migration File MIME Type Validation for Data Migration Projects

Data migration projects fail in predictable ways, and one of the most common is format mismatch: a file the source system accepted without complaint that the target system rejects because its actual type doesn't match its declared extension. Deliteful's File MIME Type Detector runs content-based MIME inspection across your migration batch and returns a structured report so you can resolve format issues before cutover.

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During system migrations — SharePoint to Google Drive, legacy DMS to cloud storage, on-premise to S3 — files accumulate years of inconsistencies: extensions changed manually, format conversions that updated the file but not the name, and placeholders or zero-byte stubs that were never cleaned up. A pre-migration MIME audit identifies three categories of problems: files whose type doesn't match their extension, empty files that should be excluded, and genuinely unrecognizable files that need human review before migration proceeds.

The tool outputs a tab-separated .txt report — filename and MIME type, one row per file — that integrates directly into a migration checklist or can be diffed against the expected file manifest from the source system. The report is deterministic: the same file always produces the same MIME type, making it reproducible across validation runs.

How it works

1
Create a free Deliteful account
Sign in with Google in about 3 clicks — no credit card or lengthy onboarding.
2
Upload the migration batch
Upload up to 50 files (2GB total max) from your source system for inspection.
3
Review and act on the MIME report
Download the tab-separated report, identify mismatches and empty files, and resolve issues before your migration cutover.

Frequently asked questions

How should I use MIME type detection in a data migration workflow?: Run MIME detection on each batch before migration. Compare the detected types against the expected types from your source system manifest. Files flagged as application/octet-stream or with mismatched types should be reviewed before being migrated to the target system.
What file types are supported for MIME detection?: Supported types include PDF, XLSX, XLS, CSV, DOCX, TXT, PNG, JPG, JPEG, WEBP, ZIP, JSON, TAR, TGZ, and TAR.GZ. Each file can be up to 50MB; batches support up to 50 files or 2GB total.
Will the tool modify my files during detection?: No. MIME detection is a read-only operation. Your uploaded files are inspected but never modified. Only the detection report is returned as output.
What does application/octet-stream mean in the context of migration?: application/octet-stream means the tool could not match the file to a known format. In a migration context, this is a signal to manually review the file before migrating it — it may be corrupted, an unsupported format, or a file type the target system cannot handle.

Create your free Deliteful account with Google and validate your migration batch for MIME type mismatches before your next cutover.