12 Free itch.io HTML5 Upload Receipt and WASM MIME Cross-Check Tools (2026)

Troubleshooting spine—post-upload curl -I, cache-bust, post_upload_mime_ok; this list is the bookmark stack.
Start here: when upload UI says success but live URL fails

First-publish sibling—export preset, zip layout, instantiateStreaming on initial itch publish.
Use when: never passed MIME on first upload

Official upload contract—zip layout, browser targets, and SharedArrayBuffer toggle for threaded exports.
Pro tip: read before fest-week re-upload loops

MIME requirement—why application/wasm matters and what browsers reject.
Use for: CI error message literacy

Label gate—itch_html5_upload_receipt + itch_public scope row when MIME is green but channel_label_match fails.
Pair with: GX multi-channel resource below

Triple-channel spine—VERSION file, GX + Steam + itch receipt rows on one build_label.
Pair with: wasm MIME receipt

Channel identity—channel_label_match before adding itch wasm URL to facilitator README.
CTA: one git SHA, three uploads

Post-boot sibling—MIME passes but browser demo dies after alt-tab; distinct from CDN cache MIME.
Best for: Godot HTML5 fest demos

Threaded export lane—hang after MIME fix often means SAB/COOP, not octet-stream.
Enable when: threads on + itch SAB toggle

Receipt validation—require post_upload_mime_ok, tested wasm_url, and cdn_cache_bust fields.
Use for: CI fail-closed

Receipt home—add wasm_mime_receipt + itch_upload_ok before sharing play link.
CTA: block HTML5 promotion on fail

Strategy framing—why itch sits beside GX and Steam for browser-first studios.
Use for: producer buy-in on MIME gates

Weekly gate—attach curl -I screenshot for itch wasm beside installed demo smoke.
Pro tip: incognito test