FAQ: Wrapping/ Unwrapping/ TRC21 Token

Here I’d like to address some of the most frequently asked questions recently about wrapping/unwrapping and what TRC21 token is.

If you have any other questions about wrapping/unwrapping, please leave your comment below.

1. What is TRC21 Token?

TRC21 is a new token standard used on TomoChain network that is different than BTC or ERC20 on Ethereum.

TRC21 tokens are issued on TomoZ Protocol to bring users a much more friendly trading experience with a blazing fast speed, and extremely low gas fees that can be paid by the transaction token itself. It will also be supported by TomoP Protocol to enable a bunch of privacy features.

By nature, we can divide TRC21 Tokens into 2 types:
Native TRC21 Token: The tokens that are originally issued on TomoChain blockchain, like TOMO, AIS, TIIM, and etc.
TRC21 Wrapped Token: The tokens that are issued on other blockchains originally, and then reproduced on TomoChain network by locking a same amount of the native asset into a smart contract or multi-signiture wallet, like BTC, ETH, USDT, YFI, and etc.

A TRC21 Wrapped Token is hosted on TomoChain public blockchain, issued by TomoBridge, and backed by an equal amount of the underlying asset or currency. TRC21 Wrapped BTC, for instance, is a token worth the same as native BTC at any given moment.

All the tokens listed on TomoDEX are TRC21 Tokens.

More about TRC21 Wrapped Token

2. What does it mean by "Wrap/Deposit" and "Unwrap/Withdraw"?

Due to the different token standards, you can only swap your TRC21 Wrapped Token to/from the other blockchain tokens via designated bridging portals.

Swapping other blockchain tokens to TomoChain’s TRC21 Wrapped Tokens is known as to "Wrap" or “Deposit”.
Swapping from TomoChain’s TRC21 Wrapped Tokens to other blockchain tokens is known as to “Unwrap” or “Withdraw

The meaning of “Deposit” here is different from traditional centralized exchanges.
On TomoDEX, users are always in direct custody of their funds. Which means you trade directly with the funds in your wallet without having to put it into the exchange’s account.

3. How to swap TRC21 Wrapped Tokens to/from other blockchain tokens?

There are 2 options for you to swap your native tokens on other blockchains to/from TRC21 Wrapped Tokens on TomoChain.
a.) Swap via TomoBridge | Tutorial
b.) Swap via TomoDEX | Reference

4. Can I sent my TRC21 token directly to an ERC20 address, or vice versa?

In simple words, NO you shouldn’t.

TRC21 (by TomoChain) and ERC20 (by Ethereum) share almost the same address structure. The Private Key that you have for either address can be used to access the same wallet address on the other network.

In other words, the address for TRC21 and ERC20 tokens is the same, with which you can selectively access either asset depending on the network that you are on.

That also means the transaction can be sent through when you transfer your TRC21 Token to an ERC20 address, and the same vice versa, with the token standard remaining unchanged.

So yes, the transaction can be signed and sent through. But this is probably NOT what you want to do if you look to swap your TRC21 Wrapped Token to/from the native tokens from other blockchains.

5. What should I do if I mistakenly sent my TRC21 Token to an ERC20 address without wrapping/unwrapping, or vice versa?

There could be a few different scenarios:

a.) If the receiving address is your own wallet address

As explained in Q4, these two token standards share the same address and all you have to do is to switch the network.

Let’s say you send your TRC21 Token to an ERC20 address, then you can retrieve your funds by following the steps below (similar process the other way around):

  1. Log into your ERC20 wallet and export the Private Key. (It has to be the Private Key, not Mnemonics)
  2. Log into your TomoWallet with the Private Key to recover your fund. (Instead of TomoWallet, you can also choose to log into TomoDEX or TomoBridge so you can unwrap directly from there)

Note: some wallets may not come with a Private Key when you created your address, like Trust Wallet. Then you might need to contact the wallet developer to help you export your Private Key.

For Trust Wallet users, please follow this guide to export your Private Key: https://community.trustwallet.com/t/how-to-recover-funds-sent-to-a-wrong-public-address/145

b.) If the receiving address belongs to a third party (ex. an exchange)

In this case, the third party team now is holding your funds. You will have to contact them directly to help you look into their account and refund it for you.

Most exchanges are willing to do it for their users for a fee. But each company could be different and it depends on their own policy.


When I wrap BTC in an erc21 token, who has custody of my BTC?
Working on project decentralization is the key, if BTC is in the hands of the team, we are still centralized
Is there any progress in making Tomochain totally decentralized?
Thank you

We’ve written up a detailed overview of TomoBridge here:

Hope it helps you understand more about how TomoBridge works and our plan to upgrade it in the future.
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Let’s assume that I created and ERC-20 token and I want to mirror it via TRC21 to create a wrap asset. How can I do it? Is it described somewhere in the manual?

Please check out this tutorial: Issue a Wrapped ERC-20 Token on TomoIssuer and List It on TomoBridge - TomoChain Docs

Hey guys. I’ve tried 2 separate transactions: to swap my ETH into TRC-21 and another to swap BTC into TRC-21, both using the TomoBridge. Both transactions confirmed on their respective blockchains over 1 hour ago… But the Tomo Wallet is still on the “Verify Transaction” Step 2, saying “we are looking for your transaction Please stay tuned”.

How long do I need to wait?

Also – could you explain how do I unwrap TRC-21 tokens on the TomoDEX? The reference only had a screenshot to deposit the tokens, but I believe withdrawing is only done on the actual TomoChain.

Some help would be greatly appreciated.

Similar usability issue to the person above. Can devs explain why the Tomobridge step to verify transaction even exists? Should allow me to either enter a transaction hash, or funds should automatically show up on either side of Tomobridge in Tomochain wallet or Ethereum wallet. Have this hanging screen for over 30 minutes so far.

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I believe I have received your support ticket and got back to you on Telegram. Let us know if you have any other questions :slight_smile:

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The scanning process is automatic so asking users to manually enter a transaction hash doesn’t really make sense here. And as it takes time to scan and check the transaction, so it can’t be confirmed right away and show up in your wallet.
But you don’t have to stay on the scanning page. You can just close the page and the scanning would still be processed in the backend.

Yes. All solved now. Thanks!