Mainnet Swap

A mainnet swap, also called a token migration, is the exchange of tokens that a project issued on an existing blockchain for coins on the project's own blockchain once it goes live. Many projects raise money or distribute tokens before their network is ready, typically as ERC-20 tokens on Ethereum. When their own mainnet launches, holders are invited to swap those placeholder tokens for the new native coins, usually at a fixed ratio.

Mainnet swaps were common in 2018 and 2019, when several projects funded through initial coin offerings launched their own chains. Examples include EOS and TRON, which moved from Ethereum-based tokens to their own networks in 2018, and BNB, which moved from Ethereum to Binance Chain in 2019. The term is distinct from an atomic swap or a trade on an exchange; it is a one-way conversion organised by the project.

Imagine a new theme park that sells tickets before it has finished building its own ticket system. It prints temporary vouchers through a well-known printing company. When the park opens, visitors bring their vouchers to the gate and swap them for official park passes. After a while, the old vouchers stop being accepted.

A mainnet swap is that exchange of vouchers for passes. The tokens on the old blockchain were placeholders, and the coins on the new blockchain are the real thing that runs the network. Holders need to swap within the window the project sets, and they need to make sure they are dealing with the real park, not someone pretending to run the gate.

Projects organise swaps in different ways, but most follow similar steps:

1. Announcement. The project publishes the swap ratio, the dates and the supported methods, often months in advance.
2. Exchange support. Major cryptocurrency exchanges agree to handle the swap for customers who keep tokens on the platform, usually by pausing deposits and withdrawals for a period and crediting the new coins automatically.
3. Self-service swap. Holders who keep tokens in their own wallets send them to a swap contract or address, or use an official tool, and receive native coins at a new address on the new chain.
4. Snapshot method. Some projects instead freeze the old token at a set block, record every balance and recreate them on the new chain, so holders need only to import their keys into a compatible wallet.
5. Retirement. The old tokens are burned or frozen once swapped, and the project sets a deadline after which unswapped tokens may lose support.

The swap ratio is not always one to one. Some projects use the migration to change the total supply or the number of decimal places, so the number of coins received can differ from the number of tokens sent.

• Raising funds early. Issuing tokens on an established chain lets a project sell or distribute them before its own network exists, using existing wallets and exchanges.
• Moving to native functions. Once a mainnet is running, coins are needed for transaction fees, staking and governance on that chain, which the placeholder tokens cannot provide.
• Changing networks. Some projects migrate from one existing chain to another, for example to cut fees or gain features, using the same swap process.

Not every project keeps a separate representation forever. After a swap, some issue wrapped tokens back on the original chain, connected through a blockchain bridge, so the coin can still be used in that chain's applications.

• Scams. Swaps attract fake websites, messages and support accounts that ask holders to send tokens or reveal their seed phrase. Official swaps never require a recovery phrase, and phishing sites often copy official pages closely.
• Missed deadlines. Holders who do not swap before the cut-off may find their tokens unsupported or tradable only at a discount.
• Exchange delays. Trading, deposits and withdrawals may be suspended around the swap, and different exchanges may handle it on different schedules.
• Technical errors. Sending tokens to the wrong address, using an incompatible wallet or mixing up old and new tickers can lead to permanent loss.
• Price confusion. For a time, old tokens and new coins may trade side by side, and data sites may show inconsistent prices or supplies.

A mainnet swap is planned and one-way: the old tokens are replaced. A chain split or hard fork can instead leave two versions of a coin in circulation, with holders receiving both. An airdrop hands out new tokens without asking holders to give anything up. Because the names sound similar, holders are advised to read a project's official announcements carefully to know which kind of event is taking place and what action, if any, is needed.