Solana Foundation Announces @solana/web3.js v3, a Kit-Based Rebuild of the Classic JavaScript API, With a New Wallet Adapter

The Solana Foundation's developer team has announced version 3 of @solana/web3.js, the long-standing JavaScript library for building apps on Solana SOL$121.10+0.3%, together with a new @solana/wallet-adapter package. The Foundation's Solana Developers account posted on October 6, 2026 that "@solana/web3.js v3 is here". The code is a few days older than the announcement: v3.0.0 was tagged on GitHub on October 1, and a v3.0.1 maintenance release followed on October 5.

Version 3 keeps the class names that web3.js v1 code is written against, such as Connection, Keypair, Transaction and PublicKey, and rebuilds them on @solana/kit. Kit is the newer JavaScript SDK kept in the Anza GitHub organisation, whose README says the 2.x line of web3.js was renamed to Kit. Announcing the release in a post on X, amilz, a member of the Solana Foundation's GitHub organisation who authored the v3.0.1 changes, summed it up as a "familiar class-based API on top, Kit under the hood" and said Kit and web3.js "now share common signers, clients, & codecs".

npm install @solana/web3.js still installs v1

A plain npm install @solana/web3.js does not yet fetch the new version. The v3.0.0 release notes say 3.x sits on npm's next tag "until October 19, then will be promoted to latest", and the npm registry on October 6 listed latest as 1.99.0 and next as 3.0.1. Until the tag moves, developers who want v3 have to ask for it by version, with npm i @solana/web3.js@3.

The package is widely used. npm's download counter recorded 3,138,820 downloads of @solana/web3.js for the week of September 28 to October 4, 2026, a week in which the default install was still the v1 line, against 3,193,933 for @solana/kit.

Breaking changes in the v1 to v3 upgrade: async Keypair, bigint and a new default commitment

Upgrading from web3.js v1 to v3 is a code change even though the class names survive. The project's release notes list these among the breaking changes:

• Keypair.generate(), Keypair.fromSecretKey() and Keypair.fromSeed() are now async, as are Transaction.serialize() and Transaction.verifySignatures(), so each call needs an await.
• Many Connection methods return bigint values where v1 returned number.
• Account data arrives as Uint8Array in place of the older Buffer shapes.
• The implicit default commitment, the level of finality a query waits for when none is specified, changed from finalized to confirmed.
• PublicKey.unique(), the legacy Account class and the deprecated fee-calculator methods, including getRecentBlockhash, were removed.

The official v1 to v3 migration guide says "non-trivial TypeScript consumers should expect real migration work", and describes most of that work as "mechanical rather than architectural". The GitHub release also lists hardening fixes across transaction confirmation, durable nonces, websocket subscriptions and RPC response validation.

@solana/wallet-adapter v3 drops per-wallet adapters for Wallet Standard

The new @solana/wallet-adapter package provides the wallet connection hooks and interface components for apps built on web3.js v3. Its README says wallets "are discovered through Wallet Standard registration in the browser; there are no per-wallet adapter constructors", meaning an app no longer imports a separate adapter for each wallet it supports. The release notes list Sign In With Solana 1.1 support, and the README describes an option that wraps the sign-in text in an off-chain message, "which is what hardware wallets can display and sign".

The older @solana/wallet-adapter-react 0.x packages have not moved. The README points developers looking for them to the separate anza-xyz/wallet-adapter repository.

Solana's docs still call v3 a release candidate and steer new apps to Kit

The announcement and the official documentation were out of step on October 6, 2026. The solana.com page covering web3.js v3 still said the library "currently ships as @solana/web3.js@rc" and "is still a release candidate", although GitHub marks v3.0.0 and v3.0.1 as full releases.

The solana.com page is clear about who web3.js v3 is for: "It is a legacy-interop path, not a default for new work; new apps should build directly on Kit." For teams with existing v1 code, v3 is the route onto Kit's signers and Codama-generated program clients. New projects are pointed at Kit and its own wallet plugin.

The next dated step is the planned move of npm's latest tag on October 19, 2026. After that date, an install of @solana/web3.js without a version number is scheduled to resolve to 3.x.