Best file uploads for a vibe-coded app: Supabase Storage vs Vercel Blob

Who this is for: your app works, usually built with AI, and now people need to upload things: profile photos, receipts, documents. You want the files stored privately, off your server’s disk, served back only through your app, with big files going straight from the browser to storage.

Our pick: Supabase Storage (96/100). It passed every check on both runs. Its buckets are private unless you opt in, and the bucket itself refused a file type we hadn’t allowed. A stranger holding the project’s public key couldn’t read, list or upload anything. If you ever leave, its S3-compatible API works with standard S3 tools.

Runner-up: Vercel Blob (96/100). It also passed everything, with the fewest surprises and the clearest docs of the two. It’s the natural choice if your app is hosted on Vercel. Two things put it second: Vercel’s API makes new stores public unless you ask for private, and there’s no S3 API or bulk export.

It’s a tie. Both scored 96 on both runs, so we ran each a second time, as our rubric requires. The tie-breaker is safe defaults, which Supabase wins.

Gotchas

Supabase: send Cache-Control: no-store from Edge Functions. In our first run, after we deleted a file, our upload API kept redirecting to it. The function code was right. The CDN in front of Edge Functions had cached our earlier redirect because the response had no Cache-Control header (cf-cache-status: HIT). We didn’t find this in the docs. Fix: set Cache-Control: no-store on API responses that change.

Supabase: a signed link can outlive a delete. In our re-run, a 60-second signed link we’d handed out before the delete kept serving the deleted file until it expired, about 55 s later. Fix: keep signed links short-lived, or stream private files through your app as we did with Vercel.

Vercel Blob: ask for private explicitly. The dashboard and CLI make you choose private or public. Vercel’s REST API, which AI agents and Vercel’s MCP use, defaults to public when you leave the setting out. Tell your AI tool to create a private store. In a private store, files can’t be fetched without a token (we got 403).

Both: approve direct uploads on your server. Big files go straight from the browser to storage, but only after your server hands out a short-lived permission (Supabase: a signed upload URL; Vercel: a client token). Check the user is logged in before issuing it. Both vendors’ docs say so. Our test app skipped login to keep the test equal.

Scores

Scored with our published rubric. Tested 2026-10-16. Both tools scored the same on both runs.

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The 8 checks: upload, download with a matching checksum, list with the right size, delete (then a 404, and any earlier storage link dead within 60 s), no secret in the browser, strangers can’t read, list or upload, a 10 MB image sent straight to storage, and an HTML file rejected by the storage itself.

What it costs

All runs cost $0 on the free plans, with no card.

• Supabase Free: 1 GB file storage, 5 GB egress plus 5 GB cached egress, 50 MB max upload size. Free projects pause after 1 week of inactivity, with a limit of 2 active projects. Pro starts at $25/month (checked 2026-10-16).
• Vercel Blob on Hobby: 1 GB storage a month, 10,000 simple and 2,000 advanced operations, 10 GB data transfer, shared with your other Vercel usage. You’re never charged on Hobby. If you go over, Blob stops working until 30 days pass (checked 2026-10-16).

Caveats

• Different setups, same API. Each tool ran the same upload API the way its docs suggest: Supabase in a Supabase Edge Function, Vercel Blob in Vercel Functions. Supabase hands out a short-lived storage link on download. With Vercel we streamed files through the app, as Vercel’s private-storage docs show. Upload speeds are logged in the evidence but not scored.
• Order matters. Supabase ran first, so Vercel’s run reused the check script and lessons.
• Vercel test project. We couldn’t create a new Vercel project with our access, so the Vercel runs used a preview deployment of an existing test project. Details are in the test script’s amendments.
• No login in the test app. Both apps let anyone call the upload API, to keep the comparison equal. Add login before you launch: see adding login to your app.
• Runs were done by an AI agent following vendor docs only.

Next step: put the files’ details in a database. See our tested pick for a database for your vibe-coded app. Charging for downloads? See taking payments in your app.

Before you launch: check your app’s security. See our vibe coding security check.

Not tested yet

• Cloudflare R2. It has to be turned on in Cloudflare’s dashboard first; queued for a person.
• Firebase Cloud Storage. Needs a console click to enable on our project; queued.
• Cloudinary and UploadThing. Both need a browser signup; queued.

This page has no affiliate links yet. Every link goes to the tool’s own homepage. Affiliate deals never decide a pick, and a tool with no affiliate program can still win. How we make money.