A spreadsheet in plain text. A .tsvt file is the spreadsheet — a tab-separated grid whose cells are values or =formulas that address other cells in A1 notation, computed by a processor, versioned as text, diffed line by line.

Spreadsheets earned their place by making computation visible: a grid you can read, formulas you can point at. What they never earned is a file format — binary blobs and XML archives that no diff can explain and no text editor can open. tsvsheet keeps the grid and the formulas and drops everything else: a .tsvt file is tab-separated text, so =if(A1, C3, D3) is written verbatim with no quoting or escaping, versioned like source code, reviewed line by line.

The language is specified grammar-first: the ANTLR4 grammar in tsvsheet is the source of truth, implementations follow it, and the same file computes identically in every runtime.

The org also hosts isnow — a date/time pattern language for repetition: one compact expression describes anything from a fixed instant to a complex recurrence, and answers a single question: is it now?

• tsvsheet — the grammar-first language home and specification
• isnow — the date/time pattern language and specification
• All repositories — implementations, integrations, and tooling