# Computation

The Computation Layer covers smart contracts (automations), business logic, and workflows on XION.

### Contract development notes

WASM binaries built with the **latest stable Rust** may fail to upload to XION (`xiond tx wasm store`) because the chain does not support WebAssembly **bulk memory** instructions that newer Rust toolchains can emit.

If you run into store or validation errors after upgrading Rust, create `rust-toolchain.toml` at your **contract project root**:

```toml
[toolchain]
channel = "1.86"
targets = ["wasm32-unknown-unknown"]
```

**Why 1.86?** Rust **1.87+** stable releases may emit WebAssembly with **bulk memory** enabled for `wasm32-unknown-unknown`. XION’s `wasm store` and runtime do not support bulk memory today, so uploads can fail even when local builds succeed. **1.86** is the latest stable release known to produce upload-compatible WASM for XION at the time of writing (May 2026). When you upgrade Rust—or when XION enables bulk memory—re-test `xiond tx wasm store` and update the pinned channel if needed.

Rebuild the contract (and re-run the [CosmWasm optimizer](/xion/developers/computation/local-development/deploy-a-cosmwasm-smart-contract.md) if you use Docker) before uploading again. See also the [local environment setup](/xion/developers/computation/local-development/setting-up-env/installation-prerequisites-setup-local-environment.md#rust) guide.

### Overview

Smart contracts on XION are built using CosmWasm and enable:

* **Business Logic**: Automate workflows and processes
* **State Management**: Store and manage application state
* **Integration**: Connect with other XION features (accounts, payments, verification)

### Quick Start

Get started quickly with pre-built app templates:

* [Zero to App in 5 Minutes](/xion/developers/computation/xion-quick-start/zero-to-dapp-in-5-minutes.md)

### Local Development

Learn how to set up your development environment and deploy your first contract:

* [Setting up Environment for XION](/xion/developers/computation/local-development/setting-up-env.md)
* [Interacting with Xion Chain using Xion Daemon](/xion/developers/tools/xiond-cli.md)
* [Deploying Your First Smart Contract on XION](/xion/developers/computation/local-development/deploy-a-cosmwasm-smart-contract.md)

### Contract Library

Browse pre-built, audited contracts you can use in your applications:

* [Re-using Existing Contracts](/xion/developers/computation/re-using-existing-contracts.md)

### Integrations

Learn how to integrate with XION features:

* [Token Factory](/xion/developers/computation/integrations/token-factory.md)
* [Oracles](/xion/developers/computation/integrations/oracles.md)
* [Websockets](/xion/developers/computation/integrations/websockets.md)
* [Indexers: Optimized Data Retrieval](/xion/developers/computation/integrations/indexers.md)

### Use Cases

Explore more example applications and use cases:

* [More Use Cases](/xion/developers/computation/use-cases.md)


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