Playground (Fastest start)
The fastest way to try Covenant is in your browser. Visit playground.covenant-lang.org, no install, no Rust, no PATH setup.
Three minutes from open to deploy
- Pick an example, click Examples and choose
Hello(the simplest contract). - Compile, click Compile. The browser runs the same compiler that ships in CI; bytecode appears in the panel below.
- Deploy on MockChain, click Deploy. MockChain is an in-tab EVM simulator: deterministic, instant, free. Reset on demand.
- Interact, call actions and views from the typed UI panel. Events stream as human-readable names, not raw hex topics.
Real testnet via Sepolia
Switch the target to Sepolia and connect MetaMask. The same source compiles to Sepolia-targeted bytecode, helper-bridge addresses (CeremonyHelper, FHE/PQ/ZK helpers) are embedded automatically. Deployments take ~30 seconds.
Tour
The playground includes a 12+ lesson tour covering:
- Hello / fields & storage / actions, events, errors
- Guards (
only,given,when) - ERC-20 token, encrypted token (ERC-8227)
- FHE basics, post-quantum signatures, zero-knowledge proofs
- Cryptographic amnesia (full ceremony lifecycle on Sepolia)
- NFT (ERC-721 in 5 lines), PQ key registry (ERC-8231), external calls
Each lesson has compilable source and a “deploy and interact” step.
State persistence
- IndexedDB, your contracts persist across page reloads.
- BroadcastChannel, open multiple tabs, state syncs in real time.
- Reset on demand, clear the chain or reset everything from the menu.
When to use the CLI instead
The playground is the right answer for:
- Trying the language
- Following a tutorial
- Demos and screencasts
- Sharing a snippet with someone (deep links work)
For projects with version-controlled source, CI, multiple files, or production deployments, install the CLI: