Supabase Storage API
Supabase Storage REST API — S3-compatible object storage with Postgres RLS-based access control, enabling agents to upload, retrieve, and manage files in buckets with fine-grained per-row access policies, built-in CDN, and on-the-fly image transformation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
SOC2 Type II certified. HIPAA BAA available on Enterprise. TLS enforced. Postgres RLS integration is best-in-class for fine-grained access control. Service role key is highly privileged — must never be exposed client-side. Data encrypted at rest.
⚡ Reliability
Best When
You're already using Supabase and want file storage that automatically inherits your Postgres Row Level Security policies for per-user/per-tenant access control.
Avoid When
You need standalone object storage without Supabase, extreme scale (petabytes), or advanced video streaming capabilities.
Use Cases
- • Agents uploading user-generated content — POST to /storage/v1/object/bucket/path with JWT token to upload files that are automatically access-controlled by RLS policies
- • Secure file access — agents generating signed URLs for private bucket objects with configurable expiry for user downloads
- • Image optimization pipeline — agents using Supabase's built-in image transformation (resize, crop, quality) via URL parameters without separate image processing service
- • Multi-tenant file isolation — agents leveraging RLS policies on the objects table to ensure tenant A cannot access tenant B's files via standard Postgres row security
- • Media asset management — agents listing, moving, copying, and deleting files in organized bucket hierarchies for content management workflows
Not For
- • Massive-scale media storage (petabyte+) — Supabase Storage is suitable for typical app file storage; use AWS S3 directly for extreme scale with fine-grained cost control
- • Video streaming — Supabase Storage doesn't have HLS/DASH adaptive streaming; use dedicated video APIs like Mux or Cloudflare Stream
- • Standalone storage without Supabase project — Storage requires a Supabase project with Postgres; not available as standalone object storage
Interface
Authentication
Supabase anon key for public bucket access, service role key for admin operations bypassing RLS, or user JWT from Supabase Auth for RLS-controlled access. RLS policies on the storage.objects table control per-user file access. Service role key must be kept server-side.
Pricing
Storage pricing is part of overall Supabase project pricing. Image transformations charged per 1000 transforms on paid plans. Bandwidth included in base plan with overages. Good value when using Supabase as full backend.
Agent Metadata
Known Gotchas
- ⚠ RLS policies must be configured on storage.objects table in Postgres — agents uploading to private buckets will get 403 until correct RLS policies are set up
- ⚠ Service role key bypasses ALL RLS — agents using service role for Storage must implement their own authorization logic to avoid cross-tenant data exposure
- ⚠ File path structure is critical for RLS — common pattern is userId/filename; agents must enforce consistent path conventions to make RLS policies work correctly
- ⚠ Image transformation requires Pro plan or higher — agents using transform parameters on free plan will receive original images without transformation
- ⚠ Bucket names must be globally unique within the project and cannot be renamed — agents managing dynamic bucket provisioning must handle naming collisions
Alternatives
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Scores are editorial opinions as of 2026-03-06.