Write without switching modes
Mix headings, notes, variables, equations, units, lists, and dates. Multitac recognizes calculations while ordinary sentences stay ordinary sentences.
Multiple thoughts and calculations
Think in words.
Work in numbers.
Multitac is a notebook for thoughts, calculations, and the connections between them. Write naturally, change an assumption, and watch every dependent result follow.
Being built for iPhone, iPad, Mac, and Apple Vision Pro.
1Weekend gathering
2Planning pizza with friends.
3people = 6
4slices = people * 3
5pizzas = ceil(slices / 8)
6A short walk after dinner.
7walk = 3.5 km
8walk in miles
The source stays visible
A notebook first.
A calculator throughout.
A TAC keeps prose, assumptions, expressions, and results in one editable document. The calculation engine is deterministic, and the document remains the source of truth.
Change one assumption
Dependent values recalculate through the notebook. Cycles and broken inputs invalidate affected results instead of leaving stale answers behind.
Make values interactive
Turn inputs into editable range cards, compare two calculated lines, or plot a numeric collection. Every card still points back to source.
Two ways into the same document
Compose a TAC.
Begin with a TIQ.
Direct writing and guided conversation meet in the same editable .mtac document. You can move between them without changing formats.
TAC
Think directly on the page
A TAC is the living notebook itself: freeform text, calculations, results, cards, pins, and context together.
- Edit source at any time
- See live results beside or below it
- Keep calculations deterministic
- Open portable text formats in place
TIQ · Thought Invoking Question
Let a question shape the page
A TIQ gathers goals, values, and constraints, then proposes visible TAC source for review. Accepted changes become ordinary edits with Undo.
- Choose goal-directed or exploratory guidance
- Review, revise, apply, or discard proposals
- Keep manual editing authoritative
- Let Multitac evaluate every expression
One capability set, four native expressions
Made for each screen it runs on.
Multitac shares its documents and core capabilities across Apple products while adapting navigation, density, input, and window behavior to each one.
A compact library, push navigation, and a current-result bar that keeps editing focused.
Sidebar browsing, adaptive side-by-side work, keyboard support, and document windows.
A full library, tabs, menu commands, Undo and Redo, and separate live result windows.
Comfortable native windows, separate result panels, and system scene restoration.
Insights with boundaries
Calculation first. Suggestions second.
Multitac uses Apple’s on-device model where available to suggest connections from a bounded set of notebook entries. Generated prose stays separate from calculated results.
On deviceNo cloud AI service, API key, or remote Multitac account.
Source identifiedSuggestions identify the supplied notes and values they used. A citation does not prove the interpretation is correct.
ReviewableTIQ proposals stay visible until you apply, revise, or discard them.
User controlledMemory candidates wait for approval and can be edited, dismissed, paused, excluded per TAC, forgotten, or cleared.
AI suggestions may be incomplete or wrong. Review the source, assumptions, units, and results before relying on them.
Broad calculation support
Everyday arithmetic to dimensional models.
The language covers reactive variables, percentages, equations, collections, scientific and statistical functions, units, dates, and time zones. Currency and cryptocurrency are deliberately outside the first release.
Math & statistics
Aggregates, variance, correlation, combinatorics, logic, trigonometry, logarithms, roots, and rounding.
Units & dimensions
Compatible conversion, dimensional products and quotients, temperatures, data units, and CSS units.
Equations & collections
Sequential equations, reverse solving, arrays, integer ranges, map, reduce, sum, product, and 2×2 systems.
Dates & time
ISO dates, durations, Unix time, date differences, local time, and named IANA time zones.
Read the full language reference
Open documentationSyntax, functions, aliases, behavior, document formats, privacy controls, and current limits.