Solana JavaScript SDK v3 Connects Existing Apps to Solana Kit

Version 3 of @solana/web3.js connects familiar application tools with Solana Kit, giving developers a way to use compatible program clients while requiring changes to transaction and data-handling code.

Version 3 of @solana/web3.js had its first stable release Oct. 1, with v3.1.1 released Oct. 19. It retains classes including Connection, Keypair and Transaction, names already used in applications built with the earlier SDK. A companion adapter is available for wallet integrations in v3.

The v3.1.0 update allows a Connection to serve as a Solana Kit client. Compatible program libraries can use that connection, so applications already using web3.js do not need to set up a separate network client for those libraries.

That compatibility gives developers a way to use Kit tools alongside existing web3.js code. The familiar class names do not make v3 a direct package swap, however: several operations and data types have changed.

Key generation, transaction signing and serialization use asynchronous calls in v3. Applications that previously handled those operations synchronously need to update the code that waits for their results. Developers also need to check transaction flows that depend on the older behavior.

Network data requires similar attention. Many remote procedure call (RPC) numeric fields now use bigint, while account data uses Uint8Array. Code that processes those fields must handle the changed types.

For token-program code previously using @solana/spl-token, the v3 migration path points to @solana-program/token. Token-2022 code should use @solana-program/token-2022. Those dependencies need review alongside changes to signing and RPC handling.

Version 1 of the SDK remains in maintenance mode and receives critical fixes only. For applications moving to v3, the immediate work is adapting existing code to the new calls, data types and token-program clients.