BetterBlast

BetterBlast, formerly Email Builder, is a Nuxt application for building, previewing, and slicing HTML marketing emails. It creates and edits templates, slices design comps into email-safe layout, previews in desktop and mobile formats, and generates campaign-ready HTML. Deployment integrates with Mailchimp and Amazon SES, with Supabase authentication and organization-based access control.

The slicer grew into the interesting half of the app. It works directly on the comps already attached to an email, supports drag-and-select editing of slice bands, and proposes cuts automatically. Every accepted or corrected cut is saved as a label, and those labels train a ranker: 200 small gradient-boosted trees written in plain TypeScript that run on the Worker with no new dependency. On 233 labeled emails the trained ranker needed no edits on 24% of them, against 3.4% for the old hand-written rules. Alt text is generated per image by OCR, re-runnable on demand and guarded by a prompt before it overwrites text someone already wrote. Desktop and mobile are independent section trees rather than one layout with overrides, and an email is blocked from going out while any slice is missing a size.

Storage runs on R2 — the AWS SDK had to be swapped for aws4fetch to make uploads work at all on Workers — and an API-key external route exposes draft creation, source assets, and review-status transitions so other systems can drive the pipeline. A client preview uses caniemail support data to show how each email client will treat the markup, and Cloudflare Browser Rendering takes a full-page screenshot per client to diff against the design. Deployed on Cloudflare at betterblast.app.