The writing checker for books

Catches the slips. Knows your story. Never forgets what you decided.

First Mate fixes obvious typos as you type, checks grammar, spelling and consistency on your device, walks you through the book one pass at a time, and remembers every decision you make. Built for fiction, so your characters can talk the way people talk. It never rewrites your voice.

Get First Mate How it works

On your deviceWorks with no internet
FastAbout 120,000 words in about 5 seconds
Fiction firstDialogue belongs to the character
No metersNo credits, no limits, no locked suggestions

The promise

Eight things First Mate will never do.

Most checkers are built for business email. First Mate is built for books, and for the person who wrote them.

It never rewrites your voice

Apart from obvious typo fixes (which you can switch off), nothing in your book changes until you accept it. AI suggestions are always shown as a before and after.

It leaves dialogue alone

With Fiction mode on, grammar and style rules skip what’s inside quotation marks. A character can say “ain’t” and talk in fragments.

Your book’s words are real words

Character names, places, ships, every Source of Truth entry and your book’s dictionary are never flagged or “corrected”.

It never asks twice

Ignore something, or mark it intentional, and it stays decided for that passage, for good, by every check and every AI report.

It works on your device first

Typo fixes, spelling, grammar, style, consistency and every report run on your computer and work offline.

It has no meters

No credits, no daily caps, no locked suggestions, and no paying again per manuscript. Run it on the whole book as often as you like.

It shows its evidence

Every card says why. Every AI finding is tied to an exact quote from your page, or it isn’t shown.

It stays quiet while you draft

No marks while you write unless you turn them on. Review happens when you ask, in a panel beside the page that never covers your text.

As you type

Typos fixed before you notice.

About 390 slips that only ever mean one thing (teh, recieve, thier, alot, a lone i) are fixed the moment you type the space. A small chip shows what changed, with Undo.

Undo a fix and it learns. Press Undo, or Ctrl/⌘ Z right after, and First Mate never changes that word again in this book. Real words are never “corrected”, and neither are names or your book’s own words.

Curly quotes, one space after a full stop, and marks while you write are each a switch of their own. Marks are off by default: the page stays quiet while you draft.

Everything that happens as you type

Grammar and spelling

Checked on your device. Built for fiction.

With Fiction mode on, nothing inside quotation marks gets a grammar or style card.

Grammar runs on a real grammar engine on your device: agreement, missing or extra words, word forms. Nothing is sent anywhere, and it works on a plane.

The mix-ups that matter in fiction: lose and loose, breath and breathe, peek and peak, free rein, more then, could of. A word is only flagged when the words around it make the mix-up clear.

Name slips are checked against your book’s Source of Truth: “Caloway” when the book says “Calloway”, or a character’s name without its capital. Names, aliases and your book dictionary are never flagged.

Spelling, grammar and consistency

Fiction mode, on by default

The crew was tired, but there work wasn’t done.

Narration: checked

“Ain’t nobody sleeping tonight,” Ruth said. “Not till the nets is mended.”

Dialogue: the character’s voice, left alone

Silence. Then the bell.

Fragments on purpose? Mark them Intentional once

The Captain’s Log

A decision stays decided.

Captain’s LogFirst Mate remembers 42 decisions in this book.

Ignored here“sea-plane”Chapter 4 · hyphenation
Intentional“Silence. Then the bell.”Chapter 7 · fragment · “on purpose, it’s the cliffhanger”
Kept as isThe letter from Ruth’s motherChapter 12 · no check touches it
Rule off in this bookLong sentencesWhole book
Word is fine“Caloosa”Added to the book’s dictionary
Never auto-fix“Ruthe”You pressed Undo in chapter 2

The number one complaint about checkers is the flag that keeps coming back. You decide it’s fine, and next time it’s there again.

The Captain’s Log is First Mate’s memory for your book. Every Ignore, Intentional, Keep, Rule off, Word is fine and Never auto-fix is remembered for that book, for good. Entries are matched by the flagged words and the sentence around them, so edits nearby don’t bring a flag back.

Rewrite the flagged words themselves and the entry shows as stale, with a button to clear it. Remove any entry and First Mate can raise it again.

How the log works

Review

One pass at a time.

Instead of one wall of flags, First Mate walks you through the book in passes: spelling and typos, grammar, consistency, style, fiction craft, dialogue, then AI proofread. Each pass shows how many are left and a progress bar.

Run it on this chapter, a run of chapters or the whole book. Every card shows the sentence, a before and after, and one line saying why. Where a rule has a target, the card shows the number, and you can change it.

↓ ↑next / previous card
Enteraccept
Iignore
Nintentional
Kkeep the passage
Ffix everywhere
Escback to the page

The cards and every button on them

Spelling and typos6 of 6
Grammar3 of 11
Consistency0 of 4
Style0 of 18
Fiction craft0 of 7
Dialogue0 of 5
AI proofreadwith your AI

GrammarChapter 3

The gulls circled and ~~there~~ their cries carried over the harbour.

Use “their” for something that belongs to them.

AcceptFix everywhereShowWord is fineIgnoreMore ▾

Reports

Ten reports on the whole book. Unlimited.

For this chapter or the whole book, each metric compared with the book average. All on your device.

Reading grade

How hard the chapter is to read, against the book’s own average.

Average sentence

Words per sentence, chapter by chapter.

Dialogue share

How much of the chapter is talk.

Sentence variety

How much your sentence lengths change.

Sentence-length chart

Every sentence, drawn as a bar, so runs of the same length stand out.

Pacing by chapter

A bar for each chapter. Click one to open it.

The five senses

Sight, sound, touch, smell and taste in the chapter.

Dialogue tags

Said, asked, and the ones that stand out.

Overused words

The words you lean on, per chapter and per book.

Repeated three-word phrases

The phrases you’ve written more than once.

Compared with you, not a hidden average. Each number is shown against your book’s own average, so you see where this chapter drifts from the rest. Run them on a chapter or the whole book, as often as you like, with no AI and no internet.

All the reports

With your own AI (optional)

The story layer: critique you can check.

Connect the AI you already use and First Mate can read for story, not just sentences. Before anything is sent, it shows you exactly what will go and waits for you to press Send. Nothing on this page needs it.

Proofread with my AI

Each part of up to 1,500 words is read 3 separate times (5 in Careful mode). Only the fixes most reads agree on are shown, labelled 3 of 3 agree. Anything that isn’t on the page, touches dialogue beyond a typo, or that your device already caught is left out.

Critique this chapter

Strengths and problems, each tied to an exact quote. Quotes that aren’t on the page, or that credit a character who isn’t in the passage, are dropped, and the small print says how many. On each note choose Done, Intentional (it won’t come back in later rounds) or Reply. Each run is kept as a round.

Ask the beta readers

Four readers, each with reactions tied to quotes and a verdict on whether they’d keep reading. A reader map shows where each one was hooked, confused or bored.

You see what’s sent

Before anything goes, First Mate shows the exact text, your Source of Truth entries and the decisions it will send, and nothing leaves until you press Send. Your key stays on your device, and you pay your AI company directly: no credits, no mark-up.

The beta readers

The genre fan

Reads your genre by the shelf. Wants the promise of the cover kept.

The skeptic

Looks for what doesn’t add up. Always included, so the feedback is never all praise.

The editor

Structure, pacing and clarity.

The first-time reader

Confusion, names, and who’s who.

What the AI parts cost

A few cents a chapter.

You pay your own AI company directly, by the request, or nothing at all with a model on your own computer. First Mate never adds a fee or a credit system on top.

Estimated cost per request, worked out from each AI company’s published prices, checked October 2026. Includes the First Mate rulebook your AI reads every time. Your provider’s bill is the final word. Everything else First Mate does is free, on your device.
Where you use it	Budget AIClaude Haiku, GPT-6 Luna, Gemini Flash-Lite	Everyday AIClaude Sonnet, Gemini Pro	Top-of-the-line AIClaude Opus or Fable, GPT-6 Astra
Proofread with my AIA part of up to 1,500 words, read 3 times so only agreed fixes show	about 0.1¢	about 2¢	up to 12¢
Critique this chapterOne chapter (about 5,000 words) with your Source of Truth and your decisions	about 0.3¢	about 5¢	up to 26¢
Ask the beta readersOne reader reacts to one chapter	about 0.2¢	about 4¢	up to 20¢
Ask my AI about a cardOne suggestion card and the sentence around it	under 0.1¢	about 0.9¢	up to 4¢
A busy monthAbout 82 requests: a proofread most days, a critique and a few beta reads a week	under $1	about $2	up to $9

Why the range? AI companies charge by the amount of text that goes in and comes out, and bigger models cost more per request. A proofread sends a short passage three times; a critique sends a whole chapter once.

Keep it predictable. Set a monthly spending limit in your account with the AI company, pick a budget model for everyday proofreads, or run a free model on your own computer. First Mate shows exactly what will be sent before anything goes, and nothing goes until you press Send.

Where it runs

Aboard today, standalone soon.

Today

Inside Salt of the Page

First Mate ships with Salt of the Page 6.0 on Mac, Windows, Linux and the web. Open it with the First Mate button, the pelican in the dock, or Ctrl/⌘ Shift K. Everything is included for anyone who owns the app.

First Mate inside Salt of the Page

Coming soon

A standalone First Mate

Placeholder: say here whether the standalone edition is a browser extension, a desktop app, a paste-in web editor or a Word and Google Docs add-on, and when it lands.

Tell us which you’d use

Made by the people behind Salt of the Page

A son and his father, and one pelican.

First Mate started as the checker inside Salt of the Page, the book-writing app made by Chris and Randy of Father & Son Productions. It grew into something that deserved its own name, its own cap and its own site. The pelican scoops up the typos; the son and his father write the rules it follows.

Visit saltofthepage.com About Chris & Randy

Questions

Things writers ask us.

What is First Mate?

A writing checker built for books. It fixes obvious typos as you type, checks grammar, spelling, style and whole-book consistency on your device, reviews the manuscript in passes, and remembers every decision in the Captain’s Log. With your own AI connected, it can also proofread, critique a chapter and play beta reader.

Do I need Salt of the Page to use it?

Today, yes: First Mate ships inside Salt of the Page 6.0 and is included for anyone who owns the app. Placeholder: a standalone edition is coming; say which kind and when.

Does it work for fiction and dialogue?

That’s what it’s built for. Fiction mode is on by default, so grammar and style rules skip what’s inside quotation marks, and fragments you mean can be marked Intentional once.

Does it need the internet?

No. Typo fixes, spelling, grammar, style, consistency and every report run on your device and work offline. Only the optional AI features go online, and only when you press Send.

See every question

Bring a First Mate aboard.

Typos, grammar, consistency and a memory for every decision, on your device, with no meters.

Get First Mate How it works