# How to validate flow account on backend?

**URL:** <https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866>\
**Category:** ⚙️ Flow SDKs\
**Created:** [May 4, 2021, 9:06am UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866 "2021-05-04T09:06:41Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ytkang](https://avatars.discourse-cdn.com/v4/letter/y/ecb155/32.png) [@ytkang](https://forum.flow.com/u/ytkang)\
**Post date:** [May 4, 2021, 9:06am UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/1 "2021-05-04T09:06:41Z")

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Hi, I have a question about binding flow account with game account without any gas fee.

If a user create flow account from frontend web client,  
How to validate this flow account user in backend server?

Is there a method signing a message from client side and validate message in backend server?

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**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\
**Post date:** [May 11, 2021, 7:09pm UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/2 "2021-05-11T19:09:12Z")

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At this point this is only possible in a 10 minute window after the user signs the transaction, because signed transactions expire after 10 minutes. The team is working on a more robust solution for this, but it isn’t ready yet

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**Author:** ![ytkang](https://avatars.discourse-cdn.com/v4/letter/y/ecb155/32.png) [@ytkang](https://forum.flow.com/u/ytkang)\
**Post date:** [May 12, 2021, 2:39pm UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/3 "2021-05-12T14:39:24Z")

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I think a 10 minute is enough to verify.  
Can you explain,  
How can I verify signed transaction on backend? and  
How to create signed transaction to send to backend on client side?

Thanks

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<div class="post-metadata">

**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\
**Post date:** [May 12, 2021, 5:44pm UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/4 "2021-05-12T17:44:20Z")

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I would recommend checking out the SDK docs on Flow’s docs website: [https://docs.onflow.org/](https://docs.onflow.org/)  
Those will show you how to do this. 🙂

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**Author:** ![ytkang](https://avatars.discourse-cdn.com/v4/letter/y/ecb155/32.png) [@ytkang](https://forum.flow.com/u/ytkang)\
**Post date:** [May 13, 2021, 3:04am UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/5 "2021-05-13T03:04:07Z")

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I cannot find any signing method for custom message in js sdk.  
I’m finding a method to sign(web client) and verify(server) account without network.

like eth web3 things,

1. sign custom message with private key  
[sign](https://web3js.readthedocs.io/en/v1.2.0/web3-eth-accounts.html#sign)
2. verify it without private key  
[recover](https://web3js.readthedocs.io/en/v1.2.0/web3-eth-accounts.html#recover)

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<div class="post-metadata">

**Author:** ![flowjosh](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.flow.com/flowjosh/32/362_2.png) [@flowjosh](https://forum.flow.com/u/flowjosh)\
**Post date:** [May 18, 2021, 6:57pm UTC](https://forum.flow.com/t/how-to-validate-flow-account-on-backend/1866/6 "2021-05-18T18:57:41Z")

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@sideninja Are you aware if this is possible with any of the sdks?