ExtensionFast vs ExtensionStart

The short version

ExtensionFast is an established, AI-native kit: WXT + React + Firebase auth + Stripe payments, positioned around building features by prompting coding agents, with Web Store submission guides, asset templates, and lifetime updates. It costs $149 one-time (listed against a $249 anchor) with a 30-day money-back guarantee, and it has a longer track record as a shipped product. Those are real strengths, and if an agent-recipe-first workflow is what you want, it's a credible choice.

ExtensionStart makes a different bet: that a paid extension lives or dies on the parts you can't vibe-check: whether the paywall survives Chrome Web Store review, whether entitlements are enforced server-side, whether the built extension actually works after every change. So the kit ships 411 unit tests and 12 Playwright end-to-end specs that run against the real built extension, a CI publishing pipeline with staged Chrome rollout plus Firefox and Edge, and a gate engine that treats when the paywall appears as tested, policy-checked configuration.

Side by side

Where a cell says "not shown publicly", that's exactly what we mean: we can only verify what ExtensionFast publishes on its site and public docs. The paid product may contain more than its marketing shows; ours you can inspect via the demo and the repository tree on the home page.

Testing: the biggest verifiable difference

Both kits pitch "ship fast with agents". The failure mode of agent-driven extension development is specific: MV3 breaks silently. A missing manifest permission makes a chrome.* API undefined, a module-scope throw kills the whole background service worker, and every message from the UI hangs forever, while tsc and the build both pass. ExtensionFast's published verification step is exactly that: tsc --noEmit and wxt build (as of July 2026). ExtensionStart's e2e suite loads the built extension into a real Chromium and exercises sign-in, gate walls, content-script UI on a hostile page, and service-worker restarts; that suite exists because those failures happened and unit tests couldn't catch them.

Paywalls: gating vs timing

ExtensionFast supports paywalled features; its site shows Stripe checkout plus entitlement gating wired by agent prompt. ExtensionStart treats a second question as the hard one: when should the wall appear? The gate engine ships trigger primitives (action counts, days since install, premium-feature moments, credits), cooldowns, sign-in chaining, and four presets whose defaults encode conversion research and Chrome Web Store policy constraints: core listed functionality stays usable pre-wall, walls are dismissible by default, sign-in is never forced standalone. The reasoning and sources are in the paywall-timing evidence post.

If you pick ExtensionFast anyway

You'll be on the same stack we chose, with the same 30-day refund window to change your mind. The things to verify before you ship: how entitlements are enforced server-side, how your paywall timing holds up against Chrome Web Store's quality guidelines, and what your regression story is once agents are editing MV3 code. Those checks are worth doing with any kit, including ours.