Nebula defaults to Stellar testnet so you can explore every feature with no financial risk. When you are ready to use real funds, switching to mainnet is a single environment variable change. The two networks share the same tool interface, but differ in how you fund your wallet, which USDC issuer is used, and which on-chain contracts back treasury and identity features.
Testnet vs. mainnet comparison
| Feature | Testnet | Mainnet |
|---|
| Default | ✅ (no config needed) | Set NETWORK=mainnet |
| Funding method | Friendbot via request_funding | Fund manually with real XLM and USDC |
| USDC issuer | Circle testnet SAC | Circle mainnet issuer |
| Blend treasury | Testnet lending pools | Verify pool availability before use |
| Stellar8004 identity | Testnet contracts | Mainnet contracts |
| Transaction cost | Free (test tokens) | Real XLM fees |
Getting started on testnet
Follow these three steps to have a fully funded testnet agent ready to send payments and earn yield.
Step 1 — Fund XLM using Friendbot
Ask your agent to call request_funding. Nebula returns a Friendbot link that credits your wallet with 10,000 test XLM in seconds.
Use request_funding from Nebula
get_address), and the faucet establishes the trustline and sends test USDC automatically.
Step 3 — Set spending limits
Add MAX_PER_CALL and MAX_PER_DAY to your MCP config to authorize your agent to spend. Start conservatively and increase them once you are comfortable with the behavior.
{
"mcpServers": {
"nebula": {
"command": "npx",
"args": ["-y", "nebula-mcp"],
"env": {
"STELLAR_SECRET_KEY": "S...",
"NETWORK": "testnet",
"MAX_PER_CALL": "10",
"MAX_PER_DAY": "100"
}
}
}
}
Once funded, run Use wallet_dashboard from Nebula to see balances, limits, and treasury status all in one interactive view.
Switching to mainnet
When you are ready to go live, follow these steps in order.
1. Set NETWORK=mainnet in your MCP config
{
"mcpServers": {
"nebula": {
"command": "npx",
"args": ["-y", "nebula-mcp"],
"env": {
"STELLAR_SECRET_KEY": "S...",
"NETWORK": "mainnet",
"MAX_PER_CALL": "10",
"MAX_PER_DAY": "100"
}
}
}
}
XLM_FEE_BUFFER default is 5 XLM).
Stellar transaction fees are extremely low — typically fractions of a cent per transaction. The 5 XLM fee buffer is more than enough to cover thousands of transactions, so your agent can operate economically even when making frequent payments or rebalancing the treasury.
Use deploy_policy from Nebula with max_per_call 10 and max_per_day 100
POLICY_CONTRACT_ID into your MCP env and remove MAX_PER_CALL / MAX_PER_DAY (or keep them as documentation — they are ignored once a policy contract is set).
4. Verify Blend pool availability
Blend lending pools on mainnet may differ from testnet. Run blend_check_rates and get_treasury_status to confirm the pools you intend to use are active and returning expected APY before enabling the background rebalancer.
Never use a mainnet secret key (STELLAR_SECRET_KEY) in a testnet configuration, or a testnet key in a mainnet configuration. The Stellar networks are completely separate — a key generated for one network has no funds on the other, and sending transactions to the wrong network will fail silently or consume real fees for no effect.
Always test your full agent workflow on testnet before switching to mainnet. Testnet resets periodically, but it faithfully mirrors mainnet behavior for all Nebula features.