In fact, I do not create transactions with non-standard outputs on mainnet.
I've tested something on testnet a long ago.
Is there a way to create an OP_RETURN transaction on bitcoin client? I found this
http://coinsecrets.org/ and this
https://github.com/coinspark/php-OP_RETURN How do I use all that?
I do not use Bitcoin Core Client.
So what else do you use?