Announcing TypeScript 7.0 RC
Summary
TypeScript 7.0 RC ships a compiler fully rewritten in Go, reporting roughly 10x speed over TypeScript 6.0. New CLI flags for parallel type-checking and project building give teams direct control over concurrency trade-offs.
Microsoft’s TypeScript team has released the Release Candidate of TypeScript 7.0, the first version built entirely on a new Go-based compiler. The announcement comes from the Microsoft TypeScript Blog and marks the culmination of over a year of porting work.
What’s actually new
The compiler has been ported from the original bootstrapped TypeScript/JavaScript codebase to Go, delivering what the team reports as roughly 10x faster performance compared to TypeScript 6.0. This was a methodical port — not a rewrite — meaning the type-checking logic is structurally identical to 6.0. The editor experience now uses LSP via a dedicated VS Code extension called “TypeScript Native Preview.” Two new CLI flags arrive: --checkers controls the number of parallel type-checking workers (defaulting to 4), and --builders controls parallel project reference builds for monorepo scenarios. These flags have a multiplicative relationship — --checkers 4 --builders 4 means up to 16 concurrent type-checkers — so tuning matters. Notably, there is no stable programmatic API yet; that’s expected no earlier than TypeScript 7.1.
What it means for your config
Your tsconfig.json itself doesn’t need changes — the compiler enforces the same semantics. But there are real workflow considerations.
Side-by-side installs: Because TypeScript 7.0 ships its own native tsc binary, running it alongside 6.0 requires the new @typescript/typescript6 compatibility package. The blog details an npm alias approach ("typescript": "npm:@typescript/typescript6@^6.0.0") specifically because tools like typescript-eslint resolve typescript via peer dependencies. If your toolchain depends on the TypeScript API (custom transformers, lint rules, anything importing from typescript), you’ll likely need this alias until those tools add 7.0 support.
New flags to consider: --checkers and --builders are worth tuning per environment. The team notes that CI runners with fewer cores and less memory may benefit from lowering --checkers below the default of 4. The announcement also warns that varying --checkers counts can, in rare cases, surface order-dependent differences in results — something to be aware of if you enforce deterministic builds.
No API yet: If you maintain tools that consume TypeScript’s programmatic API, 7.0 RC is not your migration target. Stick with 6.0 via the compatibility package and wait for 7.1.
Recommended next step
Install the RC in a non-critical project or branch (npm install -D typescript@rc) and run npx tsc to compare output and speed against your current setup. If you use VS Code, try the TypeScript Native Preview extension for the editor side. For CI, experiment with --checkers values and monitor memory. If you’re setting up a fresh TypeScript project and want a clean starting config, you can generate a TypeScript config — though the config shape itself hasn’t changed in 7.0.
Read the full announcement on Microsoft TypeScript Blog → Announcing TypeScript 7.0 RC
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