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

# Why Appchains?

> The persuasive case for appchains over L2s and rollups, with benefits like sovereignty, scalability, and migration considerations

## The Appchain Advantage

Traditional blockchain deployment forces you to choose between **scalability** and **composability**. With appchains, you get both.

### Sovereignty Meets Settlement

A based appchain combines the advantages of **running an appchain** (such as customizability, scalability, and sovereignty) with the benefits of **deploying a smart contract** on its base layer (such as composability and simplicity).

**Key Benefits:**

* **Scalability** - Dynamically adjust gas limits to support high throughput and user demand
* **Stability** - Avoid "noisy neighbor" issues with tx fee isolation and dedicated execution
* **Accessibility** - Seamlessly tap into parent chain's existing liquidity and users
* **Profitability** - Capture more value with customizable fee structures and token models
* **Sovereignty** - Full control over infrastructure, fees, and brand identity
* **Simplicity** - Minimal infra to setup and manage—e.g. no duplicative oracle deployments

## Comparison: Appchains vs Alternatives

| Feature           | Traditional L2s  | Bridge Solutions    | Appchains        |
| ----------------- | ---------------- | ------------------- | ---------------- |
| **Composability** | Native           | Async (risky)       | **Synchronous**  |
| **Scalability**   | Shared resources | Single chain limits | **Dedicated**    |
| **Customization** | Limited          | None                | **Full control** |
| **Setup Time**    | Minutes          | Hours               | **Minutes**      |
| **Trust Model**   | Sequencer        | Bridge operators    | **Fraud proofs** |

## Migration Considerations

### For New Applications

* **Start with Appchains** - Build with composability from day one
* **Future-proof** - Your app grows with the ecosystem
* **Lower complexity** - No bridge integrations or async handling

### For Existing Applications

* **Gradual migration** - Start with read operations, expand over time
* **Maintain UX** - Users don't need to learn new interfaces
* **Preserve liquidity** - Tap into existing settlement chain ecosystems

## The Based Appchain Promise

We're building toward a future where **every appchain can compose with every other appchain** under the same settlement layer. This creates:

* **Unified liquidity** across all applications
* **Atomic operations** spanning multiple chains
* **Simplified developer experience** - write once, compose everywhere

## Learn More

* **Core Concepts** - Understand [based appchains](/pylon/based-appchains) and [synchronous composability](/pylon/synchronous-composability)
* **Get Started** - [Deploy your first appchain](/pylon/quickstart) with Pylon