System overview

Sendall is a Next.js app (App Router, React 19) backed by PostgreSQL through Prisma, talking to Stellar through its RPC service rather than Horizon. There's no separate backend service: API routes under src/app/api are the entire server side.

Stack

Layer	Choice
Framework	Next.js 16 (App Router), TypeScript
Database	PostgreSQL, accessed through Prisma 7
Blockchain	@stellar/stellar-sdk, talking to Stellar RPC (not Horizon)
Wallets	@creit.tech/stellar-wallets-kit, supporting Freighter, xBull, Albedo, Lobstr, Rabet, and Stellar Hot Wallet
Auth	Custom SEP-53 sign-in, JWT sessions, rotating refresh tokens (see Authentication)
Styling	Tailwind CSS 4, no component library
Testing	Vitest for unit and integration tests, Playwright for end-to-end tests against a real Freighter build

Why RPC instead of Horizon

Two operations Sendall depends on heavily are cheaper and simpler through RPC than through Horizon: getLedgerEntries, used to bulk-check up to 200 accounts or trustlines in a single call (see Check balance and checkRecipients in src/lib/stellar/balanceCheck.ts), and sendTransaction / getTransaction, used to submit and poll a transaction without needing to reconstruct its result format from a REST response. Horizon isn't used anywhere in the codebase.

Directory layout

src/
  app/
    (app)/              route group for every authenticated-shell page
      home/
      batches/
        new/
        [batchId]/
      address-lists/
      check-balance/
      demo/
    api/                 every server route, grouped by resource
    page.tsx             marketing landing page (no shell)
  components/
    shell/               AppShell: sidebar, top bar, layout
    wallet/               WalletProvider, ConnectButton
    batches/               BatchStageNav, RecipientsEditor
  lib/
    auth/                 session, refresh tokens, anon sessions, batch access
    stellar/               SIWS, RPC client, tx building, balance checks, submission
    csv/                   CSV parsing for batches and address lists
    db/                    Prisma client singleton
    wallet/                 wallet-kit initialization
prisma/
  schema.prisma

Where to go next

• Data model for the full Prisma schema and what each field means.
• Authentication for how a wallet signs in without a transaction, and how sessions stay alive.
• Transaction building for the chunking mechanism that keeps a large batch to one signature.
• API reference for every route, grouped the same way the codebase is.