What does provably fair mean?

Provably fair means the outcome of every box opening and game round is determined by a cryptographic process that can be independently verified. The server seed hash is shown before the spin, and the full seed is revealed after.

How is the roll calculated?

The roll is HMAC-SHA256(server_seed, client_seed:nonce). The first 8 hex characters are converted to a number and divided by 0xffffffff to produce a float between 0 and 1. That float selects the winning item on the weighted prize ladder.

Can Doodly change the result after I click open?

No. Because the server seed hash is published before the spin, changing the result would require changing the seed, which would break the hash match. The client seed and nonce are also tied to your account, so the result cannot be swapped.

Verified rolls

Provably Fair

Every box opening, game round and case battle on Doodly is backed by a transparent cryptographic roll. No hidden randomness, no server-side secrets after the fact.

Verify a roll Open a box

The three inputs

Server seed

A random secret generated by Doodly. You see its SHA-256 hash before the spin, and the full seed is revealed after.

Client seed

A seed linked to your account session. It makes the roll unique to you and prevents result swapping.

Nonce

A counter that increases with every roll you make. Re-using the same seed would always produce the same outcome.

How to verify

1Open any box or game. Before the result is shown, Doodly displays the server seed hash.
2After the spin, the full server seed is revealed in your history or on the verifier page.
3Compute SHA-256(server_seed) and confirm it matches the hash shown before the spin.
4Compute HMAC-SHA256(server_seed, client_seed:nonce) and convert the first 8 hex characters to a number. Divide by 0xffffffff to get the roll.
5Match the roll against the published item weights to confirm the winning item.

Code formula

roll = HMAC_SHA256(server_seed, client_seed + ":" + nonce)
float = parseInt(roll.slice(0, 8), 16) / 0xffffffff
winner = weightedPick(items, float)

The same formula is used for boxes, case battles, Crash, Mines, Plinko, Coinflip and Wheel. You can run it in any browser console or use the public verifier page.

18+ only. Provably fair does not remove the house edge — it removes hidden manipulation. Play responsibly.