Plotline

A free online graphing, scientific, basic and matrix calculator. No sign-up, works offline.

Open Plotline → tryplotline.xyz

Plotline is four calculators in one page, built so that someone using a graphing calculator for the first time can open it and start straight away. There is no account and nothing to install, and it keeps working without an internet connection after the first visit.

Calculators

	What it does
Graphing	Plots equations as you type: functions, circles and other implicit curves, inequalities with shading, polar and parametric curves. Sliders animate any variable; tap a curve to read its coordinates.
Scientific	Logs in any base, roots, powers, factorials, and trigonometry in degrees or radians, with history and ans.
Basic	A four-function calculator with percentages and big keys for phones.
Matrix	Determinants, inverses, RREF, multiplication and systems of equations, with answers in exact fractions.

Every calculator has an on-screen keypad and one-click examples you can edit.

Features

• No account. Graphs save in your browser ("My graphs"), export and import as JSON, and share as a link that carries the whole graph.
• Save as image. One tap downloads the graph as a PNG (or opens the share sheet on a phone), with a small tryplotline.xyz credit in the corner.
• Works offline. Plotline is a progressive web app: install it from Chrome, Edge or Safari on a phone or computer.
• Guides. 24 pages explain common graphs and matrix operations, from the sine graph to RREF. Each one opens the calculator with its example already loaded. Browse them in the graph library.
• Free. No ads, no paid tier, nothing behind a login.

Plotline does less than the big tools: there is no 3D, geometry, data tables or classroom mode. See how it compares with Desmos.

How it's built

Plotline is TypeScript on Vite, with no UI framework. The math is its own engine:

• Parser and compiler (src/math): LaTeX from the input is tokenized, parsed and compiled to plain JavaScript functions. The same engine powers graphing, scientific and basic.
• Renderer (src/graphing): a canvas plotter with adaptive sampling for y = f(x), marching squares for implicit curves, and shading for inequalities.
• Linear algebra (src/matrix): exact-fraction arithmetic, so an inverse comes out as 3/5 rather than 0.6.
• Pre-rendered pages (src/seo, vite.config.ts): every calculator and guide is written into static HTML at build time, with its own title, structured data and readable content, so search engines and AI assistants see real pages without running JavaScript. The build also writes sitemap.xml, llms.txt and the guide illustrations.

Math input uses MathLive.

Run it locally

Requires Node.js 20.19+ or 22.12+.

npm install
npm run dev

Then open http://localhost:5173.

Command	What it does
npm run dev	Development server with hot reload
npm run build	Type-check, then build the static site into dist/
npm run preview	Serve the built site locally
npm test	Run the unit tests (Vitest)

Project layout

Folder	Contents
src/shell	Top bar, calculator tabs and routing (old #/… links still work)
src/math	LaTeX parser, compiler and multi-line analysis
src/graphing	Expression list, sliders, keypad and canvas renderer
src/scientific, src/fourfunction	Keypad calculators with history
src/matrix	Exact-fraction linear algebra and the matrix UI
src/storage	Save, My graphs, JSON export/import and share links
src/seo	Page content, guides, FAQs and structured data
public	Icons, social image, robots.txt

Feedback

Found a bug, a wrong answer or something confusing? Open an issue or email [email protected].

Plotline is an independent project made by Aalok. It is not affiliated with Desmos, Texas Instruments or Casio.