Flow Playground

FCL: Flow Client Library

Making secure web applications powered by the Flow Blockchain

Flow Client Library (FCL) enables applications to easily integrate with all FCL-compatible wallets and other services (e.g. (Coming Soon) profiles, private information, notifications). This offers developers a strong foundation to compose their apps with existing building blocks. It’s currently supported for browser applications, and will be extended to other platforms.

With FCL, you can:

  • Integrate all compatible wallets without any custom code or code injection
  • Authenticate users
  • Query the Flow Blockchain
  • Send transactions (e.g. initializing resources, sending assets, purchasing, etc.)
  • Sign transactions through wallet integration avoiding key management

With FCL, you will eventually be able to:

  • Personally sign data via FCL Compatible Wallets
  • Request Additional User info like Emails


  • Last Updated: Mar 2nd 2021
  • Stable: Yes
  • Risk of Breaking Change: Low

The things that exists probably won't be changing much externally, we will be adding new functionality in the near future.


npm install --save @onflow/fcl @onflow/types

Getting Started

For a detailed guid explaining how to use @onflow/fcl to interact with Flow please see the Flow App Quick Start

Having trouble with something? Reach out to us on Discord, we are more than happy to help.