Finds the Swift 6 strict-concurrency blockers in your .swift files — global var, static var shared, @unchecked Sendable, DispatchQueue.main.async inside async — before you flip the language mode. Runs entirely in your browser — nothing is uploaded.
Same engine as the VS Code extension, byte for byte.
This page is the working piece. The full pack has everything below.
11 rules that name the .swift lines Swift 6 language mode rejects — 13 findings, 6 build-blocking, on the 47-line fixture
One hour of a contract iOS engineer, at the $100/hour rates common in the US market, costs more than this licence does once.
Buy the full version — $29It reads your .swift files with 11 rules and lists every line that Swift 6 language mode rejects or quietly leaves racy: top-level var, static var singletons, @unchecked Sendable, nonisolated(unsafe), DispatchSemaphore, serial-queue locking, @escaping without @Sendable, and a Package.swift still pinned to swift-tools-version 5.x. Each finding carries a line number and the replacement shape.
iOS and macOS developers who have a working Swift 5 codebase and a Swift 6 migration in front of them, especially teams whose recent code was drafted with an assistant. Assistants still emit the Swift 5 singleton and completion-handler shapes by default, so those files carry the largest share of blockers when the language mode is switched on.
A chatbot sees only the file you paste, so it never reads the swift-tools-version line in Package.swift that decides whether Swift 6 mode can be enabled at all. Flipping the flag gives you a wall of compiler errors in build order, not in triage order, and it says nothing about the warnings that leave a race in place.
Free: lint the .swift files you open, with every blocker named, its line number shown, and its fix described. That job finishes with no licence key, no watermark and no usage counter. Paid at $29 once: export one migration report covering the whole repository, every file ranked by blocking errors, in a form you can commit or read in CI.
The alternative is engineer hours. One hour of a contract iOS engineer, at the $100/hour rates common in the US market, already costs more than the licence, and a manual triage of a mid-sized app means opening every file to look for globals, singletons and semaphores by eye. The lint returns the same list in one pass.
One question, answered by the person who built it. Your email only if you want the answer sent.