> ## Documentation Index
> Fetch the complete documentation index at: https://docs.neynar.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Why Farcaster Doesn't Need OAuth 2.0

> A decentralized architecture delivers a more sovereign trust model

OAuth exists to let three separate parties (user → platform → third-party app) establish mutual trust. Farcaster is built on a decentralized architecture that collapses this triangle:

## 1. Identity & Authentication

* **User-owned keys:** A user controlled cryptographic signature proves control of a Farcaster ID—no intermediary.
* **Dev mappings**
  * Sign In with X → Sign-in with Farcaster (SIWF)
  * OAuth 2.0 Authorization Flow → Quick Auth

## 2. Data Access & Permissions

* **Open, replicated data:** Social data like casts, reactions, and profiles live on Snapchain and can be read by anyone.
* **No permission scopes:** Everything is already public; you filter what you need instead of requesting scopes.
* **Zero-cost reads:** Sync the chain yourself or hit a public indexer—no rate caps, no \$5k +/month fire-hoses.
* **Cryptographic writes:** Users can delegate a key to applications so the applications can write on their behalf.
* **Dev mappings**
  * Centralized APIs → Snapchain + infra services (e.g. Neynar)
  * Access token → no equivalent, data is public
  * Write permissions → App Keys

## Builder Takeaways

1. **Skip OAuth flows—wallet signature = auth.**
2. **Forget permission scopes—use filters.**
3. **Enjoy building permissionlessly**

## Resources

* [Quick Auth](/miniapps/sdk/quick-auth)
* [Neynar SDK for one-call Snapchain queries](/reference/quickstart)
* [App Keys](https://docs.farcaster.xyz/reference/warpcast/signer-requests)