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Math notebook

Proofline

Solve, graph, test and visualise in one notebook — with data, findings and a report.

Launch Proofline → Tutorials

Proofline is a math notebook that runs in your browser. Each cell is a real calculator — symbolic workbench, equation solver with steps, graphing, exact matrices, number theory, statistics tests, graph algorithms, Big-O crossovers, floating point, erasure coding and more — and cells can read the same datasets, so one table flows through several analyses. Batch runs, A/B variants, run history, pinned findings and a printable report turn the results into conclusions you can share.

Free · runs in your browser · no sign-up · Version 1.0.0

Proofline notebook with an outline on the left and statistics cells linked to a dataset showing their results

Screenshots

Features

  • Notebook of live cells

    Thirteen calculators as cells plus Markdown notes: add, reorder, duplicate, collapse and run them one by one or all at once.

  • Shared datasets

    Paste or import a CSV once and link columns to any cell — statistics, matrices and edge lists read the same data, and editing it marks every dependent result out of date.

  • Chained workflows

    “Continue with” turns a result into the next step: plot a solved equation, graph a derivative, fit a normal distribution to a sample, reuse a matrix result or compare another algorithm.

  • Run all with progress

    Run every cell or only the out-of-date ones in order, with progress, a Stop button, retries after rate limits and plain-language errors — typing is never blocked.

  • Batch runs over rows

    Run one cell for every row of a column or a pasted list — primality of 100 numbers, a list of equations, tricky float values — and get one results table to export.

  • Scenario A/B

    Make a variant of any cell, change one input and compare every key figure side by side with the difference B − A.

  • Run history over time

    Each run is remembered with its inputs and key figures: see how a value changed, chart it across runs and restore earlier inputs.

  • Findings dashboard

    Pin the figures that matter — a p-value, a determinant, a path cost — and see them with their trend on one dashboard.

  • Consolidated report

    One report with findings, comparisons, every result summary, figures and batch tables: print it to PDF or export it as Markdown.

  • Instant function preview

    Graph cells draw a local preview while you type; the full analysis with roots, extrema and intersections comes from the graphing tool.

  • Algorithm step player

    Step through BFS, DFS, Dijkstra, Bellman–Ford, A*, Prim, Kruskal and more on your own graph, one settled node at a time.

  • Exports

    CSV of datasets and batch tables, SVG and PNG figures, the notebook as JSON, a Markdown report and print-ready PDF.

  • Review reminders

    Export spaced-repetition reminders (.ics) to revisit a notebook after 1, 3, 7, 14 and 30 days in any calendar app.

  • App Bridge

    Send figures, tables and the report to other premium apps, or open a table or text from them as a dataset, note or equation cell.

  • Local-first notebooks

    Autosave and recent notebooks in your browser, notebook files, share links, undo/redo and Google Drive when you are signed in.

  • Same tools for scripts and AI

    Every cell is a documented usefulweb.site tool with a JSON API and MCP, and the notebook format has a published JSON schema.

Templates

Start from a ready-made project and change it to fit.

Built-in tools

Proofline uses these tools. Each one also has its own page and works on its own, in the browser, through the JSON API and through MCP.

For AI agents

Proofline runs on a deterministic engine. The same functions are available as tools with a JSON API and MCP, so scripts and AI agents get exactly the results the app shows.

  • Math Workbench – Simplify, factor, differentiate, integrate, solve, take limits, series and plots in one box.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/math-workbench/calculate · MCP math_workbench
  • Step-by-Step Equation Solver – Solve linear, quadratic, rational and radical equations or linear systems with every step shown.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/equation-solver-steps/calculate · MCP equation_solver_steps
  • Graphing Calculator – Plot up to 6 functions or parametric curves with roots, extrema, intersections and SVG/PNG export.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/graphing-calculator/calculate · MCP graphing_calculator
  • Matrix & Linear Algebra Lab – Exact-fraction RREF with steps, determinant, inverse, null space, eigenvalues, LU/QR and Ax = b.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/matrix-linear-algebra-lab/calculate · MCP matrix_linear_algebra_lab
  • Number-Theory Lab – Primality, factorisation, gcd, modular arithmetic, CRT, φ, π(n), Collatz, continued fractions.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/number-theory-lab/calculate · MCP number_theory_lab
  • Probability & Statistics Studio – Distributions, descriptive stats, confidence intervals and t, chi-square and z tests with p-values.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/probability-statistics-studio/calculate · MCP probability_statistics_studio
  • Graph Algorithm Visualizer – BFS, DFS, Dijkstra, Bellman–Ford, A*, MST, topological sort and SCCs on your edge list.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/graph-algorithm-visualizer/calculate · MCP graph_algorithm_visualizer
  • Big-O Crossover Calculator – When does c₁·n log n beat c₂·n²? Crossover points, log-log chart and run times.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/big-o-crossover-calculator/calculate · MCP big_o_crossover_calculator
  • Erasure-Coding Playground – Reed–Solomon over GF(256): encode data into k + m shards, lose some, rebuild it.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/erasure-coding-playground/calculate · MCP erasure_coding_playground
  • Floating-Point Explorer – See how IEEE-754 half/single/double store a number: bits, exact value, ULP, rounding error.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/floating-point-explorer/calculate · MCP floating_point_explorer
  • Equation Art Studio – Turn math into art: parametric, polar, Lissajous, rose and spirograph curves.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/equation-art-studio/calculate · MCP equation_art_studio
  • Regex Golf Arena – Match the left list, avoid the right list — in as few characters as possible.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/regex-golf-arena/calculate · MCP regex_golf_arena
  • Keyboard Heatmap Visualizer – Paste any text: see which keys and fingers do the work on QWERTY, Dvorak, Colemak & co.
    Tool page · POST https://proofline.usefulweb.site/api/v1/tools/keyboard-heatmap-visualizer/calculate · MCP keyboard_heatmap_visualizer

Build a project through the API, then open it in the app with a link to https://proofline.usefulweb.site/app#project=<base64url JSON>.

Import & export

Import

  • Proofline notebook (.proofline.json)
  • CSV, TSV or semicolon tables (datasets)
  • Pasted lists and tables
  • Share link (#project=…)
  • Tables and text from other premium apps (App Bridge)

Export

  • Proofline notebook (.proofline.json)
  • CSV of datasets, batch runs and result tables
  • SVG and PNG figures
  • Markdown report
  • Printable report (PDF via print)
  • Review reminders (.ics)
  • Share link

Keyboard shortcuts

Keyboard shortcuts in Proofline
KeysAction
Ctrl + EnterRun the current cell
Shift + EnterRun the current cell and go to the next one
Ctrl + Shift + EnterRun all cells
Ctrl + Z / Ctrl + YUndo / redo
Ctrl + SSave notebook file
Ctrl + OOpen notebook file
Alt + ↑ / Alt + ↓Move the current cell up or down
Ctrl + Shift + DDuplicate the current cell
J / KNext / previous cell
1 / 2 / 3Notebook, Data or Report view
NAdd a cell
?Keyboard shortcuts

Frequently asked questions

Is Proofline free?

Yes. The notebook runs in your browser and saves to your browser’s storage and to files you download. There is no account; the calculations use the same free usefulweb.site tools as their own pages.

Where are the calculations done?

Each cell sends its inputs to the matching usefulweb.site tool on this site and shows the answer. The instant graph preview, datasets, notes, the step player, comparisons and the report work in your browser. Nothing is stored on the server.

Does it work offline?

Partly. Your notebooks, datasets, notes, earlier results, the report and the graph preview stay available offline; running a cell needs a connection because the tools run on the server. Proofline tells you when you are offline and you can run the cells again later.

What is a linked dataset?

A table in the Data view. A cell field such as a statistics sample, a matrix or an edge list can read a column (or the whole table) instead of typed text. When the data changes, linked cells are marked out of date until you run them again.

How do batch runs work?

For cells with one main input (a number, an equation, a value, a regex …) Batch run calls the tool once per row of a column or pasted list, at most 200 rows, paced to stay inside the rate limit. The results form one table you can export as CSV.

Can I trust the answers?

The tools use exact arithmetic where they say so (fractions, big integers), document their methods and verify solutions where possible, but they are teaching and checking aids. For exams, publications or safety-relevant work, verify important results independently.

Can an AI agent build a notebook?

Yes. The format is published at /project.schema.json; cell inputs use the exact field names of the tool API. An agent can call the 13 tools through the JSON API or MCP and hand the notebook over as a file or an /app#project=… link.

Limitations

What Proofline does not do (yet):

  • Cells run on the server: running needs a connection and is rate limited (about 120 calculations per minute).
  • There are no variables shared between cells; cells share data through datasets and “Continue with” actions.
  • The instant graph preview understands common functions only; the graphing tool is the reference.
  • Regex golf cells only test against the puzzle (dry run); leaderboard submissions stay on the tool page.
  • Batch runs are limited to 200 rows per run and to cells with a single main input.
  • Share links carry inputs, data and notes, not results; very large notebooks are better shared as files.
  • On phones the notebook is fully usable, but long matrices and datasets are easier to edit on a larger screen.

Tutorials

Learn Proofline step by step.

  1. Your first notebook in 5 minutesAdd a cell, run a real calculator, read the result, pin a key figure and find it again in the report. No account, nothing to install.Beginner 5 min
  2. One dataset, many analysesPaste a table once, link its columns to statistics, matrix and graph cells, and let Proofline tell you which results are out of date when the data changes.Beginner 8 min
  3. Batch runs, A/B variants and run historyRun one cell over a whole column, compare two versions of a calculation side by side and see how a key figure changed over time.Intermediate 10 min
  4. Graphs, algorithm steps and chained workflowsUse the instant graph preview, chain results into the next cell with “Continue with”, and step through Dijkstra on your own road network.Intermediate 10 min
  5. Reports, sharing, exports and review remindersTurn a notebook into a printable report, share it as a link or file, hand tables and figures to other apps and schedule spaced-repetition reviews.Beginner 7 min

Ready to try it?

Launch Proofline →

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