The tool
What the DeepSeek grammar checker does
Paste a piece of writing and this DeepSeek grammar checker reads it and reports back, in plain sentences, the grammar and clarity problems it found and where they are. Agreement errors, tense drift, comma splices, run-on sentences, dangling modifiers, sentences that have lost their subject halfway through.
Be clear about what comes back, because most pages on this term are vague about it: you get a report, not a corrected document. It points at the problems and names them. The editing is yours. If what you want is text handed back already fixed, use one of the rewriter tools on this site instead, which is a different job and a different page.
The checks
What the grammar checker looks for
It reads for correctness first and clarity second, because a grammatically perfect sentence can still be unreadable.
- Agreement and tense
- Subject and verb disagreeing, or a tense that shifts mid-paragraph for no reason.
- Sentence boundaries
- Comma splices, run-ons, and fragments that were not deliberate.
- Modifiers
- Dangling and misplaced modifiers, where the sentence says something other than what you meant.
- Punctuation
- Apostrophes, semicolons used as commas, and quotation punctuation.
- Passive constructions
- Where the passive hides who did the thing, which matters more in some writing than others.
- Clarity
- Overlong sentences, stacked clauses and wording that is more complicated than the idea inside it.
How to
How to check grammar in three steps
Longer than 12,000 characters and it goes through a section at a time, one run each.
- Step 1
- Paste the text into the box.
- Step 2
- Add an instruction if you want a specific focus, then run it.
- Step 3
- Work through the report and make the changes yourself.
The DeepSeek angle
What usually goes wrong in DeepSeek-drafted text
Here is the thing a grammar checker on a DeepSeek draft often finds: not much. Model output is usually grammatically clean, because clean grammar is the easy part. The problems are one level up.
So read the clarity half of the report more carefully than the correctness half. What tends to be wrong in DeepSeek prose is sentences that all run the same length, paragraphs that announce themselves before making a point, and a hedge in front of every claim. None of that is a grammar error and all of it makes the writing worse.
Options
The instruction box, and what to put in it
There is one optional instruction field below the text box, up to 300 characters, which goes to the engine alongside your text. It is the only setting here. No dropdowns for dialect, register or document type, because there is nothing behind them.
Things worth typing: check British spelling and punctuation conventions, focus on sentence boundaries only, this is a legal document so flag ambiguity, ignore the bracketed notes. A narrow instruction gets a more useful report than a broad one.
The limits
What this checker does not give you
Some competing tools return a grammar score out of 100, an error count per category, a readability grade and a language level. Ours returns written findings, because the engine produces prose and a number laid over prose would be a made-up precision.
It also does not highlight issues inside your original text, does not check as you type, and does not take file uploads. It is a paste-in box, a run button and a report. Text is sent to our AI server for the check, which is worth knowing before you paste anything confidential.
The honest answer
Does a grammar checker catch everything?
No. A language model reading your text will miss things, and it will occasionally flag something that is correct, particularly with deliberate style choices, dialect, technical usage and quoted material. Read its findings as a second opinion rather than a verdict.
It is also not a proofreader for facts. It will not notice that a date is wrong or a name is misspelled if the sentence is grammatical. Check those yourself.
In practice
Who uses the DeepSeek grammar checker, and when
Students doing a last pass before submitting. Non-native English writers who want to know what is wrong rather than just have it silently changed. Anyone editing a draft that came out of DeepSeek and reads oddly without an obvious reason.
The report format suits people who want to learn from the corrections. If you would rather not see the reasoning and just want clean text, a rewriter is the better tool.