During the last few days of the 100 Days Of Solana challenge, I explored one of the most interesting features of Solana's Token-2022 Program: extensions.
If you're coming from Web2, think of Token-2022 extensions like middleware. Instead of creating an entirely new token standard every time you need a new feature, you simply enable additional behaviors on a mint. The token keeps following the SPL Token standard while gaining new capabilities such as transfer fees, interest-bearing balances, or transfer restrictions.
In this article I’ll walk through the three Token-2022 mints I built during the challenge, explain what each extension does, show the exact commands I used, and break down what actually happens on-chain.
1. Transfer Fee Mint
Mint Address
YwkdCKSVccVGBzVFJWAf1USvYsc6LtbHz1VVUgKtAwY
🔎 Solana Explorer
📸 Explorer View
🧠 Step-by-step: What I did
1 - I created a Token-2022 mint with transfer fees enabled
spl-token --program-id TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb \
create-token \
--transfer-fee-basis-points 100 \
--transfer-fee-maximum-fee 1000000 \
--decimals 6
2 - What this command actually does on-chain
Creates a new mint under the Token-2022 program
Attaches the TransferFeeConfig extension at initialization
Stores fee rules directly inside mint state
3 - Fee configuration explained
100 basis points → 1% fee per transfer
maximum fee = 1,000,000 → caps large transfers
decimals = 6 → token precision
💡 When would you use this?
Transfer fees are useful when every transfer should contribute to a treasury:
- Creator royalties
- DAO treasuries
- Stablecoin protocol fees
- Community token economies
The key idea is that the fee is enforced at the protocol level, not in application logic.
2. Interest-Bearing Mint
Mint Address
7LaHSfWwPprbaQAYJnFePpVxT5brDAMtNP1hFL4UbkEt
🔎 Solana Explorer
https://explorer.solana.com/address/7LaHSfWwPprbaQAYJnFePpVxT5brDAMtNP1hFL4UbkEt/token-extensions?cluster=devnet
📸 Explorer View
🧠 Step-by-step: What I did
1 - I created an interest-bearing Token-2022 mint
spl-token create-token \
--program-id TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb \
--decimals 6 \
--interest-rate 5000
2 - What happens on-chain
- The mint stores an InterestBearingConfig extension
- The interest rate is embedded into mint metadata
- A timestamp is recorded for rate calculation
3 - Important behavior
This is critical:
👉 The interest-bearing extension does NOT mint new tokens.
Instead:
- Total supply remains unchanged
- Wallets compute a displayed balance
- Interest is applied at the UI / accounting layer
💡 Why this matters
This is useful for:
- Savings-like token experiences
- Yield visualization layers
- DeFi dashboards
It separates real supply from computed value, which is a powerful design pattern.
3. Non-Transferable Mint (Soul-Bound Token)
Mint Address
2U5BgExVuYtwLV5n4LcBLNL9S2K4SpzvJaW7c7XjgvLM
🔎 Solana Explorer
📸 Explorer View
🧠 Step-by-step: What I did
1 - I created a non-transferable mint
spl-token create-token --program-2022 --enable-non-transferable
2 - I minted tokens normally
At this stage:
- Mint works normally
- Token account is created
- Balance is assigned
3 - I attempted a transfer
spl-token transfer $MINT 1 $RECIPIENT --allow-unfunded-recipient
4 - The transfer failed on-chain
Program log: Instruction: TransferChecked
Program log: Transfer is disabled for this mint
Error: custom program error: 0x25
👉 Key insight:
The restriction is enforced by the Token-2022 program itself, not the frontend.
💡 Use cases
Non-transferable tokens are ideal for:
- Identity systems
- Certifications
- Membership passes
- Academic credentials
- Reputation systems
They represent ownership that cannot be traded.
📊 Comparison of Extensions
🧠 What I Learned
Working with Token-2022 changed how I think about token design.
Before this challenge, I assumed advanced token behavior required custom smart contracts. Now I see that many real-world patterns—fees, yield, identity—are already available as composable extensions built into the protocol.
The key insight is that Token-2022 behaves like protocol-level middleware, allowing developers to configure behavior at mint creation instead of writing custom logic.
This makes token design more modular, expressive, and secure.
If you're learning Solana, I highly recommend experimenting with Token-2022 directly. Building these mints taught me far more than reading documentation alone.
Thanks for reading!
If this helped, feel free to connect and follow my 100 Days Of Solana journey.