Which bitcoin wallets let you export to a universal .wallet format?

Question

Which bitcoin wallet applications for android, windows, and mac allow you to export .wallet files that are cross-compatible with each other? Currently there are so many wallet applications out there and I just want to use as few as possible that give a sense of security if one day the app developer just stops developing for their app.

Answer 1

First you should always run backups of your *.wallet files. So that if your HDD crash you can recover your bitcoins and the private keys to be able to spend them.

In regard to be able to switch wallet app if the development stops, I feel that support for the Wallet import format(WIF) is the only requirement you need to care about. It look like this:

5KJvsngHeMpm884wtkJNzQGaCErckhHJBGFsvd3VyK5qMZXj3hS (5 in front)

or the compressed

L3p8oAcQTtuokSCRHQ7i4MhjWc9zornvpJLfmg62sYpLRJF9woSu (L or K in front)

In fact every app can export to this format, regardless of any special feature, like Deterministic Wallets. There are also hybrid web wallets that export to this format.

But there are also web wallets where you are not truly owner of your bitcoin address, because they do not allow export with this format. In fact, there is no way of being sure that the company don't have access to your private keys.

Answer 2

Thin Clients (SPV)

• MultiBit.org
  • Tools -> Export Private Keys -> Open the file you exported
• grabHive.com (Mac only)
  • Export not yet implemented

Browser Add-ons

• SpareCoins.io (Chrome)
  • Wrench icon -> Backup Wallet (encrypted)

Full Clients

• Bitcoin-Qt
  • Help -> Debug window -> Console
    • walletpassphrase {passphrase} {timeout}
    • dumpwallet {filename} (Recommended method, dumps all wallet keys in a human-readble format, into a file named filename)
    • dumpprivkey {bitcoinaddress} (Optional method, exports a private key)

Clients with Deterministic Wallets

• BitcoinArmory.com
  • Wallet Properties -> Backup Individual Keys -> Private Key (Plain Base58)
• Electrum.org
  • Export -> Private Keys -> Open the file you exported

Hybrid Web Wallets

• StrongCoin.com
  • Your Accounts -> Select one -> Decode Private Key (with passphrase)
• BlockChain.info
  • Import/Export -> Export Unencrypted -> Look for 5*, L* or K* Private Keys

Android Wallets

• Mycelium.com

  • Keys -> (Options bar |) -> Export
  • (OUT OF DATE) Key Management -> (Options) -> Export to SD card(jpg to "mycelium-export" folder), QR code or to the clipboard

• BitcoinSpinner

  • (Options) -> Settings -> Advanced -> Export private key -> QR code or clipboard

• Bitcoin Wallet (by Andreas Schildbach)

  • (Options) -> Back up Keys (encrypted)
    • openssl enc -d -aes-256-cbc -a -in

.... there will be more in time, hope to keep this answer updated