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How to launch a testnet

This document explains how the Cardano SL public testnet was launched and the configuration settings used.

Related documents:

Genesis Data

A new genesis block is created for the testnet. The parameters used to generate genesis data are specified in the testnet_launch section of lib/configuration.yaml.

All values are inherited from the mainnet_base section, unless overridden.


  • protocolMagic — this number is different from mainnet’s magic to ensure that signatures from testnet are different to mainnet.
  • requiresNetworkMagicNMMustBeJust (the default) — will ensure that the format of addresses and hence transactions are different and incompatible to those of mainnet.
  • totalBalance — 42,000,000,000 Ada — is close to the maximum possible coin value (45B Ada).
  • avvmDistr — this is the empty hashmap, unlike in mainnet which has many Ada redemption addresses.
  • fakeAvvmBalances — there are 100 fake AVVM seeds which can be used to redeem 20,000,000 Ada each on the testnet.
  • poors — Unlike mainnet which has none, there are 100 “poor” nodes with generated keys.
  • richmen — There are 7 testnet richmen, i.e. core nodes, same as mainnet.
  • richmenShare — 95%. After subtracting the total balance of fake AVVM certificates, there will be 40,000,000,000 Ada divided between the 7 rich and 100 poor nodes. A single poor node will recieve 0.05% of that total, which is 20,000,000 Ada.


The mainnet blockVersionData has been updated since its genesis. The testnet will be launched with these new parameters matching mainnet’s current blockVersionData.

maxHeaderSize2KBMaximum size of block’s header
maxProposalSize70KBMaximum size of Cardano SL update proposal
maxTxSize64KiBMaximum size of transaction

Update system block version

In addition, the update.lastKnownBlockVersion is set at 0.0.0 in the testnet_full. The nodes will refuse to create blocks if this value is higher than zero.


The testnet faucet will dispense a random amount in the range of 500 to 1500 Ada.

It is not rate limited, but automatic withdrawals are prevented with reCAPTCHA.

According to the parameters above, up to 2,000,000,000 Ada could be dispensed, though not all should be made available to the faucet.

Maintaining control of testnet Ada

IOHK will retain control of the majority of testnet Ada to minimise the risk of the testnet becoming a threat blockchain and the testnet currency assuming value.

The core nodes (richmen) control 95% of stake.

Additionally, not all AVVM certificates and “poor” addresses should be sent to the faucet.

Redeeming ADA from fake AVVM seeds

The certificate seeds are in the keys-fakeavvm directory within the output of cardano-keygen generate-keys-by-spec.

Copy one of fake-N.seed to the clipboard, then use the Daedalus wallet UI to redeem the testnet Ada.

  1. Click on the DaedalusAda redemption menu
  2. Go to the Regular tab
  3. Paste the seed into the Redemption key box.

Importing “poor” secret keys into a wallet

Copy one of generated-keys/poor/ to a secure location and then use the v0 /api/wallets/keys endpoint to import it into a wallet.

Launching a demo cluster with testnet genesis

This script will generate genesis data using the procedure described in, and then launch a demo cluster with that genesis data.

nix-build -A demoClusterLaunchGenesis -o

Connecting to the testnet

This script will connect to the running public testnet.

 nix-build -A connectScripts.testnet.wallet -o