MIME Type Lookup

Overview

A MIME type and file extension lookup API, for example the MIME type for JSON or the extensions behind image/png. MIME Type Lookup works by searching the mime-db database, which merges the IANA, Apache and nginx type lists. Returns category and default charset for an extension or MIME type, with the defining source and all associated extensions on paid plans, and accepts a full Content-Type header value such as text/html; charset=utf-8.

Live Test MIME Type Lookup Source →

Formula

One function covers the whole catalog: the first argument names the source, the next are its inputs, and the field after them says which single value lands in the cell. Formulas covers the grammar that applies to all of them.

=VERVE("mimetypelookup", A2, "count")

A2 holds the extension you are looking up. Drag the formula down and each row resolves on its own.

With literal values

Nothing has to come from a cell — typed values work the same way.

=VERVE("mimetypelookup", "pdf", "count")

Inputs

Required inputs are positional, in the order below, followed by the field. Everything else is passed as a "name", value pair after that — the same shape as SUMIFS. Premium inputs are accepted on every plan but only take effect on plans that include them.

Input	Type	Where it goes	Description
`extension`Required	string	argument 2 (A2)	File extension to lookup (without the leading dot)

What lands in your sheet

The field — the argument after the inputs — is what makes the formula resolve to one cell. Its value is a dot-path from the table below, so swapping it is how you pull a different value — one formula per column.

Seeing everything at once

Leave the field out and the formula returns the whole response instead: two columns, field name on the left and value on the right, spilling from the cell you typed in.

=VERVE("mimetypelookup", A2)

Good for exploring, not for filling down

The second row's table would land on top of the first's, and every cell after the first reads #REF! (#SPILL! in Excel). Keep one per sheet, or name a field, and leave the cells below and to the right empty.

Response fields

Paths are relative to data. Each one is exactly what the field argument accepts, so swapping it is how you pull a different value into a cell. On a plan without a Premium field the cell reads #PREMIUM(field) rather than a value, so a locked field never looks like a real answer.

Use as the field	Type	Example cell value	Description
`count`	number	`1`	Number of matching extensions found
`results`	array[1]
`results.0.extension`	string	`jpg`	File extension without the leading dot character
`results.0.mimeType`	string	`image/jpeg`	Standard MIME type that was looked up
`results.0.category`	string	`image`	File category classification such as document, image, video, audio, archive, or text
`results.0.charset`	object	`null`	Default character encoding for the MIME type (e.g., UTF-8) or null
`results.0.compressible`Premium	boolean	`false`	Whether the content type can be gzip compressed
`results.0.source`Premium	string	`iana`	Registry that defines the MIME type: iana, apache or nginx, or null for a custom type
`results.0.extensions`Premium	array	`["jpg","jpeg","jpe"]`	Every file extension registered for this MIME type, including the one looked up

Filling a whole column

Both platforms make one batched call for a column rather than one request per cell, and both cost the same — 1 credit per row looked up. How you write it differs, because the two runtimes batch at different points.

Rows 2–100 in one call

=VERVE("mimetypelookup", A2:A100, "count")

In Google Sheets, give the arguments ranges and the answers spill down from the cell you typed in. Custom functions there run synchronously and in isolation, so dragged cells cannot be coalesced — the range form is how a column becomes one call. The field is required here: a per-row two-column table has nowhere to spill. Use a full column per input (A2:A100, not A2) — a single-cell reference is read as row 1 only and the rest of the column comes back blank.

In Excel, type the formula once and fill down — no range form and none needed, because its runtime is asynchronous and the add-in coalesces the calls a fill produces into a single batched request. Do not hand VERVE.CALL a range: Excel flattens it into positional arguments, so A2:A100 arrives as a hundred separate arguments and the cell reads #ERR rather than filling.

Either way, column A holds your extension values and the answers land beside them, one row each, blank rows skipped.

When a cell doesn't fill

A failed lookup returns readable text starting with #ERR rather than a spreadsheet error, because Excel cannot show a custom message on a real error — you would get a bare #VALUE! with no reason. The trade-off is that IFERROR() will not catch it; test with LEFT(cell, 4) = "#ERR" instead. Error handling covers the rest.

Cell reads	What happened
`#ERR Not connected`	No API key saved. Open the side panel and connect your account.
`#ERR Replace <name> with a cell or value`	A preview formula was copied as-is. Swap the placeholder for a cell reference.
`#ERR No "x" in mimetypelookup`	An option name this source does not take. The message lists the ones it does.
`#ERR No data point "…"`	The field path is not in the response. Check it against the table above.
`#PREMIUM(field)`	The field exists but your plan does not include it.
`#ERR Out of credits`	The cycle's credits are spent. Usage resets on your billing date.

Before the formula works

The add-in reads the API key you saved once in the side panel — the key never goes in the formula, so a shared sheet does not leak it and a collaborator without access simply sees the last calculated values.

Install the add-in for Google Sheets or Excel.
Open the side panel and sign in, or paste a key from your dashboard.
Type the formula above into any cell.

Use cases

File Upload Handling: Validate and identify file types during file upload processing in web applications
Content-Type Headers: Set correct Content-Type headers for HTTP responses based on file extensions
File Processing: Determine how to process files based on their MIME type in data pipelines
API Development: Configure proper content type handling in REST APIs and file serving endpoints

Other ways to use MIME Type Lookup

Set up MIME Type Lookup on VerveSheets, or reach the same source a different way. Your VerveSheets account and credits work on all of them — one key, one balance.

Call it as a REST APIOne HTTPS endpoint and an x-api-key header, with SDKs for Node, Python and .NET.APIVerve →Reference →

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.VerveKit →Reference →

Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.VerveContext →Reference →