In order to find your Safe address, you need (1) either the account address of one of its owners or (2) the transaction hash of the transaction that created your Safe.
(1) You know one of the owner accounts
Let us assume you know that
0x448E4E6DD37523A5c7804D75a67754c24bFbFb32 is an owner of you Safe but you forgot the address of your Safe.
There is an endpoint on the Safe transaction service that returns for a given address, the list of Safes that address is an owner of:
Replace the placeholder with your owner address. Make sure it is checksummed, meaning it uses both upper- AND lowercase letters instead of just lowercase letters.
Open this url in your browser and you will find your Safe address. In our example, this would be: https://safe-transaction.gnosis.io/api/v1/owners/0x448E4E6DD37523A5c7804D75a67754c24bFbFb32/
And the missing Safe address is
(2) You know the transaction hash of the creation transaction
Let us assume that you have the transaction hash of the transaction that created your Gnsois Safe account, for example by identifying the transaction in the wallet that created the account (such as your Metamask wallet):
First, open this transaction hash on Etherscan: https://etherscan.io/tx/0xb4e2ba0676d38454fb618ab700944db2e41e21a0bf54b79aa57a3e95a38798c6
Logs tab and look for the
ProxyCreation event. In the
Data field of that event you will find the address of your Safe.
The missing Safe address in our case is again