A notepad calculator: type plain lines, get live, checked results — natural math, variables, percentages, dates, unit and currency conversions, and reusable live answer tokens.

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Variables & Functions	Natural Calculations
Name values, apply functions, and totals stay live	Arithmetic, percentages, section totals and dates — as plain lines
Units & Currencies	Linked Answers
Convert distance, temperature, mass and currency in one line	Reuse any result as a bubble that stays in sync

For the full, exhaustive reference of every construct — line forms, operators, functions, bases, percentages, money, units, currencies, dates, network queries, number presentation — see the docs/SYNTAX_REFERENCE.md canonical reference (documents current main) and the documentation index for the settings and appearance guide, docs/EXPORT_AND_PRINT.md for PDF export and printing, and docs/UPDATES.md for the secure in-app update model. The published documentation lives at https://numlex.tech/docs/.

Numlex reads ordinary notebook text — no formula syntax, no cell references. Each line is evaluated strictly; anything it cannot parse stays quiet instead of guessing.

hotel = 1240          1,240
hotel + 10%           1,364
$240 + 10% tip        $264.00
sqrt(144)             12
room = 180 × 4        720
round(room / 3, 2)    240
sum(1, 2, 3)          6
20 km to meter        20,000 m
100 C to F            212 F°
Jan 10 + 12 days      Jan 22

Every line above runs through the real engine — these are its exact, deterministic outputs, with no live rates involved. Declare values with name = expression, use percentages and money with the same grammar ($240 + 10% tip), and do date arithmetic on plain month names (Jan 10 + 12 days). Named money reads naturally too: apple = 5$ prices one apple, and 2 apples + 3 apples totals in dollars.

Currency codes are case-insensitive: 500 usd, 500 UsD and 500 USD all mean 500 US dollars (usd, eur, gbp, … — any of the 166 supported ISO codes). A line may combine currencies with + and -: the first money operand sets the result currency and every other operand is converted into it with the current rates, so with 1 EUR = 1.1 USD 500 usd - 300 eur is $227.27. Symbols and codes mix freely ($500 - 300 eur, 500 usd - €300), and plain scalars or percentages keep their meaning (500 usd - 20 = $480.00, 500 usd - 10% = $450.00). Currency × currency and currency ÷ currency stay errors (never a silent USD²), money × scalar and money ÷ scalar still work, and physical units still never convert implicitly. If the needed rate pair is missing, the answer is the explicit Rates unavailable state — never a guessed number, a partial sum or a stale rate. The same rules apply to named values and to answer tokens: balance = 500 usd - 300 eur stores US dollars, and TOKEN - 300 eur converts into the token's currency. Constants are offline, so a single-currency constant (Rent = 500 usd) resolves normally while a mixed-currency constant stays inactive.

The engine shares one pure function registry across every scalar path — free expressions, assignments, constants and unitless answer tokens. Names are case-insensitive, arguments are full expressions (nesting included), and a function-shaped line is strict: an unknown name, a bad arity, a bad comma or a domain failure is a precise error, never a guess.

• sqrt, abs, round(x) / round(x, d) (ties round away from zero)
• min, max, sum, average — variadic, one or more arguments
• pow(b, e) — same finite contract as the ^ operator
• ln(x), log(x) (base 10), log(x, b), log10(x)
• sin, cos, tan — radians; asin, acos, atan
• radians(d) and degrees(r) — explicit unit helpers
• int(x), bin(x), oct(x), hex(x) — exact integer projection with its own presentation radix (hex(255) → 0xFF)
• count, median, stdev (sample, n−1) — variadic statistics
• rand(lo, hi) — a uniform random integer in the inclusive range (dynamic per epoch)

Inside argument lists a comma separates arguments; a comma directly before exactly three digits is still a thousand separator, so sum(1, 234) is two arguments while sum(1,234) is one grouped literal — and 1,234,567 outside a call is one number, exactly as before. Built-ins activate only in call position: a variable or constant named sum still works in sum + 1, and sum(1, 2) calls the function. Answer tokens join the same engine when they are unitless: sqrt(<token>) and <token> ^ 2 evaluate with the token as a live argument, while unit-bearing and money tokens passed to a function or to ^ fail safely instead of losing their unit.

A standalone total line sums the unitless calculation answers above it — since the sheet start or the previous total — and starts a fresh section below. The answer renders semibold under a gray rule placed exactly between the neighboring answers, and it behaves like any other answer: Copy, per-answer rounding and tokens all work, and wrapped logical lines keep their gutter number centered on the block. Money, unit-bearing quantities, booleans, dates and error rows never enter a section total.

The window also has a persistent bottom Total panel (turn it off under Settings → General → Show total bar). It is a separate, dimension-agnostic contract: it adds the evaluated magnitude of every ordinary scalar answer row once — unitless numbers, unit-bearing quantities (2 kg), money ($3), named scalars and exact integers — and shows one plain unitless number with no unit conversion, no FX normalization and no unit or currency suffix (2 kg, $3 and 4 EUR total 9). Derived aggregate rows (inline total, subtotal, grand total and tag aggregates) are excluded so the totals never double-count, and booleans, dates, locations/DMS, error and blank rows do not contribute. Per-answer rounding and number-format overrides never change the bottom Total; it follows the global notation and regional settings.

Write 10 km to meter — in works just as well (10 km in meter).

• Around 290 measurement units across length, area, volume, mass, time, speed, pressure, force, torque, energy, power, flow and viscosity, plus temperature and fuel economy.
• 166 fiat currencies with live rates: codes (10 EUR to USD), symbol forms ($100 in EUR) and English names (10 Indian rupees to Japanese yen).
• Rates are cached locally for an hour; if the network is unavailable, Numlex keeps serving the last good table.

Type weather in London for the current 2 m temperature in Celsius degrees (shown C°). The lookup goes to Open-Meteo with no key and no location permission — only the city you typed is ever sent. Readings are cached for ten minutes, and the last good value keeps showing if the next refresh fails, so a flaky connection never blanks your sheet. The city name is tinted exactly like any other unit, in Light, Dark and custom styling alike.

The temporal subsystem (shipped in 4.9.0) turns the notebook into a small time-aware calculator: calendar arithmetic, clock math, timezones, timestamps, durations, timecode, work calendars and special dates all read as ordinary lines.

May 5, 2026 + 30 days        Jun 4, 2026
3:30pm + 2 hours 15 minutes  5:45 pm
2am PST to GMT               10:00 am
April 1, 2019 3:30pm as iso8601  2019-04-01T15:30:00+02:00
5.5 minutes as timespan      5 min 30 s
03:10:20:05 at 30 fps + 50 frames  03:10:21:25
workdays from April 12 to June 15  44 workdays
days until Christmas          344 days

Timezone conversion (time in Paris, 6pm Sydney in Chicago) runs on a bundled, hash-verified offline catalog; work calendars use 25-country public holiday data for 2019–2035 and can be configured under Settings → Dates & Times (hours per workday, holiday region, custom timezone aliases). Unsupported regions, years or invalid dates fail closed with an exact error rather than guessing; time, timestamp and timecode rows are excluded from totals and are not tokenizable. See the canonical syntax reference for the strict forms and every lane.

Finance phrases (shipped in 4.9.0) build on the same money grammar and strict lane discipline:

$1,000 after 3 years at 7%                      $1,225.04
$1,000 for 3 years at 7% compounding monthly    $1,232.93
monthly repayment on $10,000 over 6 years at 6%  $165.73
annual return on $1,000 invested $2,500 returned after 7 years  13.99%
$300 + VAT                                      $345.00
income tax on $75,000 in US                     $8,114.00
what is $1,000 from 1990                        $2,537.53

Compound interest, present value, ROI and CAGR, loan/mortgage payments and interest, sales tax/VAT/GST, estimated 2026 income tax for 10 countries and BLS CPI-U inflation (1913–2025 plus a provisional 2026 point and an explicit-rate future form) all resolve offline from versioned, hash-verified catalogs. Sales tax uses the region preset you configure under Settings → General → Tax (with a documented unset-versus-zero distinction); income tax is a coarse national estimate with per-country provenance and fail-closed rules, not tax advice, and inflation answers are deterministic for the bundled data snapshot. Missing rates stay the explicit Rates unavailable state. See the canonical syntax reference.

Double-click any answer — or type an operator on a new line — and Numlex inserts a live token at the caret or selection. A token is a small bubble that always displays the current value of its source line: change the source and the bubble updates immediately. Several distinct bubbles may reuse the same earlier line — each keeps its own identity and follows the live value, as in the screenshot above. If a source line stops evaluating, its tokens stay in place and show the remembered Line N label instead of a stale number.

Right-click (or Control-click) any answer for its native menu: Copy Answer puts the exact displayed value on the clipboard; the discrete 0…10 dp slider re-rounds just that answer without touching the source line; Delete Line removes the source line. The menu is fully native, so it follows the system appearance in Light and Dark.

Work in named sheets with line numbers, syntax tinting and a live results column. Sheets are grouped by the one-level folder tabs pinned to the bottom of the sidebar: the built-in General tab plus any custom folders you create. Selecting a tab filters the sheet list only — your editor and cursor never jump. The main window resizes down to a 260pt content height for compact desks; the default stays 800×600 and the sidebar and answers keep scrolling safely. The answer column is adjustable (140–400 pt, default 200): drag the thin divider between the editor and the answers — left grows the column, right shrinks it — or set an exact width in Settings → Styling → Answer column. The choice is app-global (it is never part of a sheet's .nlx), and in a narrow window the column is capped so the editor always keeps at least 280 pt.

Choose Auto (follow macOS), Light or Dark for the whole app, pick the Dock/App Switcher icon (Dark — the signed bundle icon and the default — or Light), then tune font size, font design, role colors and the answer column width, decimal places, input helpers, line numbers, interface language, the currency display, and an option to hide the sidebar button once collapsed — reopen it any time with ⌃⌘S (Control-Command-S) or View > Toggle Sidebar. Define up to 100 app-wide constants (PI = 3.141592653589793, Sales Tax = 20%, Side = sqrt(4)) that are available in every sheet and resolved live through the same strict engine — function arguments included. See docs/SETTINGS_AND_APPEARANCE.md for the full settings reference: seven icon-over-label tiles across the top of the window (General, Editing, Numbers, Dates & Times, Constants & Units, Styling, About) with one focused page each — language, appearance, the application icon and the sales-tax configuration live together in General, Dates & Times owns the work calendar and custom timezone aliases, and About carries the app identity plus the update controls. The floating Total's statistic (Sum, Average, Count or Median) is a native checked context menu, persisted app-globally and never part of .nlx.

A genuinely new install opens on a short, native calculation bloom: ten real calculations in the app's own editor palette stream into two airy columns around the app icon, gather into it and disappear, and the icon answers with a one-shot silver splash (fine monochrome rays, a soft expanding wave and a few droplets). The splash settles into a compact final lockup: the icon grows from its streaming footprint to a large 152 pt frame, the official slogan Think freely. We’ll do the math. fades in beneath it in the same neutral tone, and a single monochrome Get Started button — silver on Dark, graphite on Light, matching the icon rather than the accent colour — appears last. The slogan itself is a two-line monochrome lockup (a rounded clause answered by an italic serif, then a quieter rounded line answered by a compact monospaced one), revealed as one calm block. The whole sequence runs once for roughly two and a half seconds and stops; with Reduce Motion the large icon, slogan and button are simply there, immediately usable, with no staged animation at all.

Pressing Get Started records a small versioned marker (welcome-v1) in the app's data directory (separate from your settings and sheets), mounts the notebook underneath and then slides the welcome panel up out of the content bounds like a curtain over 0.75 s — the window itself never moves, resizes or loses its titlebar. The notebook, its sidebar and TextKit are not created behind the welcome, and focus lands in the editor only after the curtain has cleared.

Existing installs never see the bloom: any prior artifact — the store (even corrupt or unreadable), the currency-rate cache, the weather cache or the location cache — counts as an existing install, and in that case the completion marker is recorded best-effort without touching those files. Closing the window before pressing Get Started leaves no marker, so the bloom returns next launch. Your Light/Dark/Auto choice and app icon are never changed by any of this.

Package 7 adds a plain-text structure on top of the notebook: a trailing #tag marks a row for total of #tag / average of #tag / count of #tag / median of #tag aggregates; an exact --- divider starts a new section; subtotal (± a percentage, optionally named) sums the section and grand total sums the successful subtotals. Four new functions join the registry — count, median, stdev (sample) and rand — alongside the natural forms median of …, count of …, standard deviation of … and random number between X and Y. Random values are stable for the current epoch and reroll only on a semantic edit or the explicit ⌘R (Recalculate Dynamic Values); they are never tokenizable. Right-click the floating Total to switch it between Sum, Average, Count and Median.

Sheets persist locally in Application Support. The only network traffic is the background rates refresh plus Open-Meteo lookups for weather in … lines you type yourself — never GPS or location data. From the File menu, import or export any sheet as a .nlx file, export it as a PDF, or print it (⌘P). Drag a sheet onto a folder tab to re-file it.

The File menu owns exactly four sheet commands: Import Sheet… (⌘I), Export Sheet (.nlx)… (⌘E), Export Sheet as PDF… and Print… (⌘P). PDF export and printing open one options sheet — font family, face and size, syntax highlighting, original line numbers, footer Total, comment/#-marker filters and an inclusive line range — and every option is session-only and clamped to the selected sheet. Both draw one immutable resolved snapshot through one deterministic paginated renderer: the live editor, caret, selection, highlights and tokens are never touched, answer tokens keep their real capsule labels, the exported footer uses the current footer statistic over the exported rows only, writes are atomic, and the whole path is fully offline. See docs/EXPORT_AND_PRINT.md for the complete contract.

• macOS 26 or later, Apple Silicon (arm64).
• 4.9.5 is the current release. 4.8.0 was the first release with secure in-app updates, so anyone on 4.8.0 or later (including 4.8.0 itself) can check, verify and install later versions in the app; users still on 4.7.0 or earlier have no updater and install the current release manually once, then update in-app. See docs/UPDATES.md.
• Download the .dmg from the latest release, open the plain (unstyled) disk image — it contains only Numlex.app and an Applications shortcut — and drag Numlex.app into Applications.
• Numlex is ad-hoc signed and not notarized. On first launch, Control-click (or right-click) Numlex.app, choose Open, and confirm the prompt.
• Verify your download with the checksums file from the same release:

shasum -a 256 -c SHA256SUMS

You can also install Numlex from the project's own custom tap:

brew install --cask Qulierm/tap/numlex

This uses the project's custom Qulierm/tap, not the official Homebrew cask repo. Numlex is ad-hoc signed and not notarized, so on first launch you still have to Control-click (or right-click) Numlex.app, choose Open, and confirm the prompt.

Requires macOS 26 with the Swift 6.2 toolchain; Xcode Command Line Tools are enough (xcode-select --install).

swift build               # debug
swift build -c release    # release

The engine suite covers 1,305 shared cases, runnable two ways:

swift test                # Swift Testing suite (full Xcode toolchain)
swift run NumlexTests     # standalone runner (Command Line Tools only)

Package a signed app bundle:

Scripts/build-app.sh [debug|release]   # produces .build/Numlex.app

The five offline catalogs (timezones, holidays, income tax, CPI, tax presets) ship inside the app as one SwiftPM resource bundle at the STANDARD location Numlex.app/Contents/Resources/Numlex_NumlexCore.bundle. Scripts/build-app.sh takes that bundle from the exact bin path of the requested configuration and fails closed on any missing dataset, so the packaged app is fully self-contained and relocatable.

At runtime the catalogs resolve through the centralized ResourceLocator (Sources/NumlexCore/Models/ResourceLocator.swift) in a fixed order: standard packaged location first, then the SwiftPM-style layouts a swift build / swift run / test process uses, then the current directory. It never touches the SwiftPM-generated resource accessor (whose hardcoded developer build path and trap made older packaged builds crash on first launch when installed outside the original build directory) and contains no developer-absolute path. A missing or corrupt dataset is a nil catalog — fail closed, never a crash.

Deterministic packaging checks (no GUI required):

Scripts/relocated-app-smoke.sh   # copies the app OUTSIDE the repo and proves the copy loads all five catalogs via --validate-packaged-resources
Scripts/validate-dmg.sh <dmg>    # plain-DMG contract incl. the standard bundle location and no root-level bundles

Numlex is available under the MIT License.