Tafla, calculations you can understand and trust

Ask Tafla a question with numbers in it and the answer is worked out on a board, step by step. A language model writes the formulas, and the GRID spreadsheet engine computes every number.

Try Tafla

An AI assistant gives you an answer. You have to take its word for it.

A chat answer

Paying an extra $200 a month pays off your mortgage about 6.8 years sooner.

On Tafla's board, the new payoff time of 23.2 years with the mortgage balance falling to zero, feeding a circled Time saved card that shows its formula, original term minus new payoff time, 30 minus 23.2, equals 6.8 years. — The same answer in Tafla

Tafla lays the calculation out where you can see every step and change any number, so you don't have to take its word for it.

Tafla shows you every step, and lets you change the numbers

See every step

The calculation is laid out on a board, each step with its formula in plain words, and a walkthrough explains it line by line.

Change any number

Move a slider and everything that depends on it updates instantly.

Trust the arithmetic

The model only writes formulas. The GRID engine computes every number, the same way Excel would.

285/285

Sessions where every step added up

Tafla benchmark

99.9%

Formula compatibility with Excel

GRID Spreadsheet Benchmark

6–19x

Cheaper with smaller models

Tafla benchmark

Drag a slider and every number updates instantly

Every input on the board is a slider or a switch. Move one and every step that depends on it recalculates.

The GRID engine runs in the browser, so a change never goes back to the AI or to a server. There is nothing to wait for and no tokens to pay for, in Tafla and in your own product.

The language model writes formulas. The GRID engine does the math.

A first question in Tafla. You ask. The language model sets up the calculation and sends formulas to the GRID calculation engine, which does all the arithmetic and sends values back until the model is built. The board, in your browser, draws each step as it arrives and then plays the walkthrough, which a voice can read aloud. — The model never sends a number it worked out itself. How Tafla works, step by step

Build the same thing into your product with GRID

Spreadsheet engine

Computes every formula the way Excel does. Runs in the browser or on your servers, so data stays inside your product.

About the engine

Agent tools

Give your own agent the same moves Tafla makes. Write formulas, read results and goal seek, over MCP or your own SDK.

About agent tools

Viewer and editor

Show people the spreadsheet behind an answer, for viewing or editing, right inside your product.

About the viewer About the editor

Frequently asked questions

Is Tafla a GRID product?

No, Tafla is a personal project by Hörður Ragnarsson, who works at GRID. It's built on the GRID spreadsheet engine. The story behind Tafla.

Does it work with our existing spreadsheets?

Yes. The engine opens .xlsx files and calculates them as they are, with the same functions, error values and edge cases as Excel.

Could we have an AI write our own formula engine?

It will get the common functions working quickly and look done long before it is. Excel's edge cases are mostly undocumented. Why you shouldn't vibe code a spreadsheet engine.

Where does the engine run?

Inside your application. It is a headless TypeScript library that runs in the browser or on a Node.js server, with no Excel install and no calls to an outside service.

How is it licensed?

Install it from npm with a free evaluation license. When you are ready to ship, talk to us about a commercial license.

Get started now

Install the engine Tafla runs on from npm with a free evaluation license. When you are ready to ship, talk to us.

Get started

Commercial licensing

Tafla, calculations you can understand and trust

Ask Tafla a question with numbers in it and the answer is worked out on a board, step by step. A language model writes the formulas, and the GRID spreadsheet engine computes every number.

Try Tafla

An AI assistant gives you an answer. You have to take its word for it.

A chat answer

Paying an extra $200 a month pays off your mortgage about 6.8 years sooner.

Tafla lays the calculation out where you can see every step and change any number, so you don't have to take its word for it.

Tafla shows you every step, and lets you change the numbers

See every step

The calculation is laid out on a board, each step with its formula in plain words, and a walkthrough explains it line by line.

Change any number

Move a slider and everything that depends on it updates instantly.

Trust the arithmetic

The model only writes formulas. The GRID engine computes every number, the same way Excel would.

285/285

Sessions where every step added up

Tafla benchmark

99.9%

Formula compatibility with Excel

GRID Spreadsheet Benchmark

6–19x

Cheaper with smaller models

Tafla benchmark

Drag a slider and every number updates instantly

Every input on the board is a slider or a switch. Move one and every step that depends on it recalculates.

The GRID engine runs in the browser, so a change never goes back to the AI or to a server. There is nothing to wait for and no tokens to pay for, in Tafla and in your own product.

The language model writes formulas. The GRID engine does the math.

Build the same thing into your product with GRID

Spreadsheet engine

Computes every formula the way Excel does. Runs in the browser or on your servers, so data stays inside your product.

About the engine

Agent tools

Give your own agent the same moves Tafla makes. Write formulas, read results and goal seek, over MCP or your own SDK.

About agent tools

Viewer and editor

Show people the spreadsheet behind an answer, for viewing or editing, right inside your product.

About the viewer About the editor

Frequently asked questions

Is Tafla a GRID product?

No, Tafla is a personal project by Hörður Ragnarsson, who works at GRID. It's built on the GRID spreadsheet engine. The story behind Tafla.

Does it work with our existing spreadsheets?

Yes. The engine opens .xlsx files and calculates them as they are, with the same functions, error values and edge cases as Excel.

Could we have an AI write our own formula engine?

It will get the common functions working quickly and look done long before it is. Excel's edge cases are mostly undocumented. Why you shouldn't vibe code a spreadsheet engine.

Where does the engine run?

Inside your application. It is a headless TypeScript library that runs in the browser or on a Node.js server, with no Excel install and no calls to an outside service.

How is it licensed?

Install it from npm with a free evaluation license. When you are ready to ship, talk to us about a commercial license.

Get started now

Install the engine Tafla runs on from npm with a free evaluation license. When you are ready to ship, talk to us.

Get started

Commercial licensing