StrongCoin
StrongCoin was a browser-side hybrid bitcoin wallet. Private-key material was encrypted in the browser before storage on StrongCoin's servers, so the operator held only encrypted keys. A forgotten passphrase could not be recovered by StrongCoin. The service offered printable paper backups of key pairs and import of keys in Mini private key format. Historical fee copy stated an add-on of 0.01 BTC per spend transaction.[1]
Closure
On 28 April 2026 the StrongCoin blog post We are closing down stated that StrongCoin is closing down and will no longer provide its Bitcoin wallet service. Users who believe they still have an account with a bitcoin balance were asked to contact support. The notice states that starting one year from that notice, StrongCoin will charge a 2% fee for all users who have not removed their funds. It also offers to forward users who cannot remember the password to their encrypted key to a recovery service.[2]