About this tool

A small grid, an exact route count

Gridwalk helps you check a hand-made grid puzzle, compare obstacle placements and understand how a route count builds from neighbouring cells.

The page counts all right-and-down routes from the upper-left cell to the lower-right. It also shows one deterministic example route and the count to every cell. That combination makes a total easier to inspect than a number alone. A zero-route layout is a useful outcome, while malformed input is clearly identified as an input error.

One focused calculator

This independent website contains one calculator, its method guide, worked examples and supporting pages. The grid is an abstract mathematical puzzle, not a geographic map. No diagonals, backward moves, costs, random route sampling or real-world navigation are included. Cells and moves are distinguished explicitly, including the single-cell empty route.

How the tool is built

Exact integer arithmetic preserves the full count without rounding or reduction modulo another number. The calculator reuses predecessor counts instead of enumerating every route. A backward pass selects one right-first example that can actually reach the destination. The guide states the recurrence, grammar and limits; the examples show how obstacles change the totals.

Keeping it free

The calculator has no account requirement or payment step. This release has no active advertising, analytics or consent-platform loaders. Advertising could be added after the host's own configuration and applicable consent coverage are separately verified. Publisher metadata and ads.txt do not mean that ads are approved or serving. There is no guarantee of traffic or earnings.

Corrections and feedback

The contact page uses an existing verified shared portfolio forwarding alias. For a report, name Gridwalk and include a small non-sensitive grid, the displayed count and what you expected. Keep the puzzle rules explicit so the issue can be reproduced.