MIME types

This MIME Types tool does two fast lookups:

• MIME type → extensions (example: $\texttt{application/pdf}$ → $\texttt{.pdf}$)
• Extension → MIME type (example: $\texttt{.png}$ → $\texttt{image/png}$)

1. Choose a direction: Mime type → extension or File extension → mime type.
2. Pick a value from the dropdown. (Tip: you can scroll quickly — it jumps to the current selection.)
3. Read the result chips right below the selector. Use the Share button if you want a link that preserves your selections.

When it may not be suitable: if you need guaranteed type detection from file contents. Extensions and declared MIME types can be wrong; for strict validation, you should inspect the bytes on the server.

• Prefer setting a specific $\texttt{Content-Type}$ over defaults like $\texttt{application/octet-stream}$.
• Treat extension-based lookups as a convenience, not proof. For security checks, verify file content server-side.
• Some extensions map to multiple types; different ecosystems may “prefer” different answers.
• If you’re naming downloads from binary content, pair this with our Base64 tools to ensure consistent naming.

There’s no “math” here — the tool performs deterministic lookups in a mapping database. You can think of it as two functions:

Example mapping (shown as a step-by-step “calculation”):

Note: extensions are treated as lowercase without the leading dot in the internal mapping, but the UI shows them as $\texttt{.ext}$.

• Lookups are based on a mapping database; they do not inspect the actual file bytes.
• Real systems may prefer different MIME types for the same extension.
• For security-sensitive upload validation, always verify content server-side.

• IANA Media Types Registry
• MDN: Content-Type header
• RFC 2046: Media Types