Step 1 — Go to supabase.com, sign up free, create a new project.

Step 2 — In your project, go to SQL Editor and run this:

create table items ( id uuid default gen_random_uuid() primary key, user_id uuid references auth.users not null, name text not null, brand text, category text, size text, condition text, cost numeric default 0, listed numeric default 0, sold numeric, status text default 'active', platform text, notes text, added_at timestamptz default now(), updated_at timestamptz default now() ); alter table items enable row level security; create policy "Users own their items" on items for all using (auth.uid() = user_id) with check (auth.uid() = user_id);
Step 3 — Go to Project Settings → API, copy your Project URL and anon public key.