A regex to search for would be even better

Don't hate me for using AI.

^(?:0x[a-fA-F0-9]{40}$|
[13][a-km-zA-HJ-NP-Z1-9]{25,34}$|
bc1[a-zA-HJ-NP-Z0-9]{25,90}$|
[LM3][a-km-zA-HJ-NP-Z1-9]{25,34}$|
r[0-9a-zA-Z]{24,34}$|
(?:bitcoincash:)?(q|p)[a-z0-9]{41}$|
X[1-9A-HJ-NP-Za-km-z]{33}$|
D{1}[5-9A-HJ-NP-U]{25,34}$)
would work with Bitcoin Legacy, SegWit, Bech32, Ethereum, Litecoin, Ripple, BCH and Monero.
This is great.
To reduce the workload, I would only include the following networks:
- Bitcoin
- Any network whose addresses start with "0x" (Ethereum, Binance Smart Chain, Arbitrum, Polygon, etc.)
- TRON
That covers 99.9% of contests, giveaways, bounties and signature campaigns.
Some block explorers allow you to have private address tags. To give you an idea of the popularity of each network, I have the following # of tagged addresses in each block explorer:
bscscan - 1105 addresses
etherscan - 486 addresses
tronscan - 42 addresses