This is a quiet place to write. The page is yours: no toolbars, no ribbons, nothing asking for your attention. When you start typing, the controls fade away. Move the mouse and they come back.
Margin can call on Claude as a careful reader, but only when you ask. It never writes for you. It catches mistakes, notices patterns, and remembers what happened on page forty. Every change it proposes waits for your approval.
The lighthouse keeper had been alone for too many winters. Every evening she climbed the hundred and twelve steps, lit the lamp, and wrote one line in her log — the weather, the ships, the colour of the sea. There was never anything else to report, until the night a second light answered hers from the empty horizon.
Every word yours.
Every word read.
Margin is a quiet, native Mac app for writing, with a perceptive editor in the margin. It catches your mistakes, maps your story and answers questions about your manuscript. It never writes a word for you, and every change it suggests waits for your yes.
A new page in your library, named by its first line. Press Esc to go back.
The principle
Most AI wants to write your book. Margin wants to read it: closely, honestly and all at once, the way a good editor does. Then it hands the pen back. Every sentence on the page is one you wrote.
01
No rewrites, no ghostwriting, no “here’s a better version”. Proofreading fixes are mechanical by design: a built-in check throws out any “correction” that rewrites more than a couple of words.
02
Every fix waits for your yes: accept with ↩, dismiss with ⌘⌫, skip with ⇥. Every change is undoable, and ⇧⌘H hides every mark at once.
03
Notes, the Story brain and Ask describe what you wrote, with quotes that jump to the page. They never invent, and never tell you what should happen next.
The editor in the margin
Open the companion with ⌘2. Every tool reads your whole book at once, keeps its marks pinned to your words as you write on, and remembers which draft it read.
01 Proof ⇧⌘P
Spelling, grammar and punctuation, marked in place: a wave for spelling, a line for grammar, dots for punctuation. Each fix shows exactly what changes. Accept it, dismiss it or skip it.
Only the paragraphs you’ve changed are read again. Teach it the names you invented with Learn Word, and it never flags them in that book again.
It neverrephrases. A built-in check refuses any “correction” that rewrites more than a couple of words.
All suggestions reviewed.
In the morning she rowed to Wexley herself, which she had not done in two years. The harbourmaster had her report and laughed. and Tobias sat by the fire in the Anchor while listened, and she described the signal: three short a pause, then one long one.
This book’s words CarrickWexleyPrynne
⌘] next · ⌘[ previous · ↩ accept · ⌘⌫ dismiss
02 Notes ⇧⌘E
Clarity, pacing, repetition, rhythm, consistency, dialogue and point of view, listed under the chapter they sit in. And a note when something is working especially well, because an editor should tell you that too.
After the first reading it reads only what you’ve changed, with the whole book as context. Resolve a note and it’s gone.
It neveroffers replacement wording or ideas.
Editor’s notes
A close reader’s margin notes: what’s unclear, what drags, what repeats, and what’s working. Observations only, never rewrites.
Pencilling questions in the margin…
2Two2
Pacing
“Prynne stayed four nights at the lighthouse.”
Four nights pass in a sentence, right after a scene that took a page. If the speed is the point, it works; if not, the middle may feel skipped.
Point of view
“He had a soft voice and very clean hands.”
Close on Ione, this reads as her judgement of him, and the only time her view of someone is this pointed.
3Three2
Working well
“It was not full of figures. It was full of dates”
The turn from figures to dates is the hinge of the story, and the reader finds it with Ione.
Consistency
“Her blue eyes met his”
In One her eyes are “grey as the water in March”. If the change is deliberate, a reader may want a sign that it is.
No notes yet
Read the text when you’re ready. After the first reading, Margin reads only what you’ve changed.
03 Story brain ⇧⌘B
Logline, synopsis, themes, cast, places, relationships, a tension arc, scenes and a timeline. Then the plot holes and continuity slips, each with a quote that jumps to the page.
Writing essays? It maps the thesis, the concepts, the shape of the argument, the logic gaps and the claims that need support.
It neverinvents anything, or suggests what should happen next.
Story brain
A map of what’s on the page: plot, people, places, how they connect, and where the logic slips. It describes; it never invents.
A lighthouse keeper on a remote point sees an impossible answering light and discovers that her late father, and the Board that wants to close her station, have been watching it for thirty years.
FictionLiterary mystery
Synopsis
Ione Marsh has kept the Carrick Point light alone for eleven winters. Her brother Tobias brings supplies and news that the Board plans to automate the light, and that an inspector, Aldous Prynne, has arrived in the village.
Themes
Solitude and signalIone’s isolation is defined by lights that go unanswered; the second light is the first thing that ever replies.
InheritanceIone unknowingly repeats her father’s watch; the ledger turns a private mystery into a family one.
ObsolescenceThe threat of automation frames the keeper’s role as something about to vanish.
Characters 4
Ione Marsh
Protagonist, keeper of the Carrick Point light
Aldous Prynne
Inspector from the Board
Tobias
Ione’s younger brother
Father
Former keeper, deceased
Places 2
Carrick Point
Primary setting
Wexley
Nearby harbour village
Tension
Scenes 6
The keeper
Ione’s routine; Tobias brings news of automation and of Prynne.
Ione · Carrick Point · Autumn
Unknown light
The second light appears; Ione logs it.
Ione · Lantern room · 9 November, night
The Anchor
Ione reports to Wexley; Prynne believes her.
Ione · Wexley · 10 November
Four nights
Prynne observes the light and records it in silence.
Ione · Carrick Point · Mid-November
The ledger
Ione discovers thirty years of sightings and her father’s hand.
Ione · Kitchen · Fourth night
Up the steps
The light flashes; Ione climbs toward the lamp.
Ione · Stairs · Same night
Continuity · major
Ione’s eye colour changes
Her eyes are described as grey in part One but blue in part Three. Nothing in the text suggests a change.
Her eyes, grey as the water in MarchHer blue eyes met hisTimeline · moderate
The father’s sightings vs. eleven winters
The ledger begins thirty years ago, and Ione has kept the light for eleven winters, yet the text presents this as her first sighting. If the light comes every November, she should have seen it ten times before.
kept the Carrick Point light for eleven wintersevery November for thirty yearsOpen thread · minor
What happens to keepers who answer
Prynne says every keeper who answered left within the year; the text leaves open whether they chose to leave or something happened to them.
has left the Point within the year04 Story map ⌘3
Every character, place, object and group in your book, and every relationship between them, as a map you can rearrange. Drag a node. Click one to see what it’s tied to. In Margin, double-click to find it in the text.
Story map
10 characters, places & things · 11 connections
Drag to arrange · click a node for details · double-click to find in text
05 Rhythm
Sentence-length rhythm, echoed words, fillers and adverbs, at a glance. Try it: change the passage below, or paste your own.
It neversends anything anywhere. Rhythm is computed entirely on your Mac.
Your words
Measured in your browser, the way Margin measures on your Mac. Nothing you type here is sent anywhere.
Rhythm
The shape of your prose. Nothing here is sent anywhere.
Sentence rhythm
Echoes within 50 words
Softeners & fillers
Paragraph length
06 Jottings ⇧⌘J
Select a passage, press ⇧⌘J, type a line. Margin files it under Character, Plot, World, Theme, Craft or To-do, and a thin rule in its colour sits beside the passage. Edit the passage and the jotting follows. Delete it, and the jotting keeps the old words until they come back.
Or speak it. Your Mac writes it down, and Margin never sends the recording anywhere. Expand draws a note out: what it’s getting at, what the page already says, and a question only you can answer.
It neverwrites, brainstorms, or suggests what should happen. Expand works only from what’s on the page.
Ione said nothing. She watched the boat until it was a fleck against the headland, and then she climbed the stairs.
It was the ninth night of November when the second light appeared. Three short flashes, a pause, then one long one.
“Three short, one long,” he repeated. He had a soft voice and very clean hands.
“Because the last ship to answer that light was the Margaret Dunn, in 1894.”
Jottings
Your own notes, on a passage or the whole piece. Expand draws a note out against the page, and never writes for you.
Character
Ione said nothing. She watched the boat until it was a fleck against the headlandIs her silence grief or pride? I don’t know yet.
Plot
the last ship to answer that light was the Margaret DunnPlant the wreck earlier. Tobias could mention it on the jetty.
Theme
Three short flashes, a pause, then one long one.Every light in this book is a message nobody answers. Until the last one.
Craft
He had a soft voice and very clean hands.Too neat? Let one detail about Prynne be wrong.
07 Ask ⇧⌘K
Questions about your own text, answered with citations you can click. Each chat is its own conversation. Highlight a passage to ask about just that.
Ask it for wording and it says no, then shows you what that part of your text does now, and asks what you intend. It’s the strictest editor you’ll ever have.
It neverwrites, rewrites, suggests edits or picks between versions, even when pressed or told it may.
Ask your manuscript
Questions about your text, or a passage you highlight, answered with citations. It helps you think it through, and never writes, suggests edits, or picks a version for you.
08 Reading
Margin reads your manuscript and your jottings, names the threads you’re turning over, and suggests two or three short, great readings for each: books under 150 pages, stories, essays and long-form pieces from established publishers and writers.
Each one says what the work does, and where it touches your thread.
It nevertells you what to write, or how to use what you read.
Assistive reading
Short, great reading chosen from your manuscript and jottings, to help you think through what you’re working out: mostly books under 150 pages, fiction and nonfiction, and the best writing online.
Keeping watch alone
Ione’s eleven winters tending a light nobody answers: solitude as a duty she has chosen, and what it has made of how she sees.
Ione Marsh had kept the Carrick Point light for eleven winters, and in all that time nobody had ever answered it.Train Dreams
Denis Johnson
Fiction · 2011 · about 120 pages
A whole life lived mostly alone in the Idaho woods, told in a few long breaths. It shows how far a story can go on a nearly silent character, and how much weight small, repeated tasks can carry.
Find itThe Solace of Open Spaces
Gretel Ehrlich
Nonfiction · 1985 · about 130 pages
Essays on years spent alone on Wyoming sheep ranches, where isolation turns into a way of paying attention. It is close to the question your opening asks: what looking at nothing for years does to a person.
Find itA signal passed down
The second light that father and daughter both recorded: an inheritance nobody explains, and whether answering it is the point.
The earliest entry was in her father’s handwriting.The Signal-Man
Charles Dickens
Fiction · All the Year Round · 1866 · a 30-minute read
A railway signalman alone in a cutting is haunted by a warning that keeps coming back at the same hour. Dickens never settles whether it is real, and the story’s tension lives in that withholding.
Find itThe Turn of the Screw
Henry James
Fiction · 1898 · about 120 pages
Apparitions recorded by a single witness, whose account is the only evidence. It is the classic study of how a text can keep a sign both real and doubtful to the very end.
Find itThe writing room
A centred serif column, palettes made for hours of reading, and controls that fade while you type and come back when you move the mouse. Everything you need to finish a book, and nothing that pulls you out of it.
Six palettes
Paper, Linen, Dune, Dusk, Night and Moss, or Automatic to follow your Mac. Pick one: this page changes too.
Focus mode ⇧⌘F
Prynne stayed four nights at the lighthouse.
On each of them the second light flashed its pattern at exactly the same hour, and on each of them he made a small mark in his ledger and said nothing at all.
On the fourth night Ione found the ledger open on the kitchen table.
It was not full of figures. It was full of dates.
Everything else dims, and every mark clears from the page. Or focus on the sentence instead.
Markdown, shown as formatting
## Two
She wrote it in her *neatest* hand: **Unknown light, SW.**
She checked the chart ~~three times~~ twice.
Symbols hide until you’re on the line. Hover one to edit it.
Typewriter scrolling ⇧⌘T
A whole book
120,000
words in a book, so every tool reads all of it at once. Fill one and Margin celebrates.
Ambience
Nothing is recorded. In Margin it’s synthesized live on your Mac, and here it’s synthesized live in your browser. Pick one.
Ambience
Music
Synthesized live on your Mac.
Snapshots ⇧⌘S
Snapshots
The Second Light · 4 snapshots
Automatic ones thin out as they age: all from the last day, then one a day for a month, then one a week. The ones you save are kept.
Chapters ⌘4
LibraryChapters
3 chapters · 525 words
Drag to reorder, and their notes go with them. Your book stays one plain Markdown file.
Export ⌘E & Publish ⇧⌘U
Export to PDF, Word, RTF, HTML, Markdown or plain text, with real footnotes, tables and pictures. Publish copies your post into your publication’s editor, formatting intact, and private %%notes%% stay behind.
Publish to
yourname.substack.com
Title & subtitle
The Second Light
Copy Markdown Copy Post
Your words are yours
Margin keeps your manuscripts in your own iCloud Drive or on your Mac, never on Margin’s servers.
Your Mac & iCloud DriveWhere your writing lives
Margin’s serverPasses it on. Keeps none of it.
Claude, by AnthropicReads, answers, never trains on it
Every piece is a plain Markdown file in your library folder, with Margin’s notes and snapshots beside it. Stop using Margin tomorrow and your book is still a file any app can open.
Your text goes to Claude only when you use an AI tool or save a jotting for sorting (you can switch that off), and only the part that’s needed. On the way it passes through Margin’s server in memory only, never written to disk or logs.
Anthropic may not train its models on your writing, and Margin doesn’t either. You keep every right to your work.
Spoken jottings are recorded and written down by Apple’s speech recognition on your Mac. Margin never sends a recording anywhere.
Settings › Privacy lists each one: when it was sent, which tool, how many characters and tokens. The log never contains your text.
Offline mode blocks every request. The editor, your jottings, Rhythm, snapshots and export all keep working without a connection.
No analytics. No tracking. No ads. Not in the app, and not on this website.
Read the privacy policyPlans
Every plan starts with a 7-day free trial on the Mac App Store and includes every tool. Plans differ only in how much reading you ask of Margin each month.
Essays, stories and newsletters, or a light month on a book.
Price at launch
A novelist’s normal month: drafting, or revising a chapter at a time.
Price at launch
An intensive month of revision on a whole book.
Price at launch
If you stop, your writing doesn’t. Margin still opens, exports and shows in Finder everything you wrote.
A big month? Top up when you need to. What you buy never expires.
Cancel any time in your App Store settings, in a couple of clicks.
.margin folder, and Margin’s server never sees any of it.Margin will read every word of it, and never write one.