Check Grammar

Overview

Grammar Check sends your `text` to a helper service built on harper-core 3, the Rust library behind the open-source Harper grammar checker, with an APIVerve layer on top that tunes it for automatic correction. Leading and trailing whitespace is trimmed first; line breaks inside the text are kept. An empty string returns a 400 error, and an input the checker service rejects also returns a 400 rather than a 500.

The text is parsed as Markdown, so inline code, links and URLs are not checked. The English variant is detected from the spelling the writer already uses and returned in `dialect`; British, Canadian, Australian and Indian spellings such as colour or theatre are not changed to American ones. Harper's grammar rules then run over the text, covering subject-verb agreement, a/an, their/they're/there, its/it's, your/you're, could of, repeated words, sentence capitalisation and several hundred common word-choice mistakes. Wording and style advice (shorter phrasings, en dashes and similar preferences) is not reported, because applying it automatically would rewrite correct text.

Spelling suggestions are ranked by how people actually mistype: swapped letters, a missing or extra double letter, a wrong vowel, a neighbouring key and words that sound alike count as smaller mistakes than arbitrary edits, and common words rank ahead of rare ones. A word typed in lowercase is never corrected to a proper noun, and the case you typed is kept, so TOMOROW becomes TOMORROW. Capitalised words in the middle of a sentence are treated as names and left alone unless they are one slip away from a known place or name. Acronyms, words with digits, camelCase identifiers and common technical terms such as JSON, OAuth or npm are not flagged.

`errorCount` is the number of reported problems and `modified` is true when there is at least one. `corrected` is built by applying the first suggestion of every problem, working from the end of the text backwards so earlier offsets stay valid; overlapping problems are reduced to one first, so every correction applies cleanly.

Each entry in `corrections` carries `rule` (the kind of problem, for example `Spelling`, `Agreement`, `Repetition`, `Capitalization` or `Word Choice`), `message`, `position.start` and `position.end` as character offsets into the trimmed text, and `suggestions`, the replacement strings for that span, best first. An empty-string suggestion means delete the span. Offsets count characters, not bytes, so they line up with JavaScript string indexes for most text. On the Free plan `corrections` is null and only the summary fields are returned.

Live Test Check Grammar 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("grammarcheck", A2, "modified")

=VERVE.CALL("grammarcheck", A2, "modified")

A2 holds the text 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("grammarcheck", "This is a sample text with a grammatical error.", "modified")

=VERVE.CALL("grammarcheck", "This is a sample text with a grammatical error.", "modified")

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.

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("grammarcheck", A2)

=VERVE.CALL("grammarcheck", A2)

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.

Filling a whole column

Both platforms make one batched call for a column rather than one request per cell, and both cost the same — 20 credits per row looked up. How you write it differs, because the two runtimes batch at different points.

=VERVE("grammarcheck", A2:A100, "modified")

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 text 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.

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.

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

Use cases

Content Management Proofing

Flag grammar mistakes in submitted blog drafts and substitute corrected sentences before publishing articles to readers.

Customer Support Messaging

When agents write replies in ticketing desks, the system uses the error count to warn them of uncorrected typos.

Resume Intake Screening

Job portals scan cover letters during applicant uploads, noting whether the text was modified to preserve clean candidate profiles.

Student Essay Feedback

Learning management platforms pass student submissions to display the number of errors and return properly formatted text.

Other ways to use Check Grammar

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

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