There are as many perspectives on what makes a decentralized app (DApp) as there are DApp developers. This section defines the principles that Blockstack advocates for DApps operating within its platform.
- Blockstack DApp principles
- DApps serve users
Blockstack DApp principles
An application is considered a Blockstack DApp if it adheres to three principles.
I. Users own their data
DApps do not store or replicate user data. Users own their application data independent of and outside of the application. A Blockstack application is only considered decentralized if its users control where their data is hosted and can prove that they created the data.
Blockstack applications meet this principle if they use the Gaia storage system. Users may sign and/or encrypt their data in Gaia end-to-end. All files in Gaia are addressed by a user identifier, an application’s hostname, and a filename. Through Gaia, users can prove data ownership and restrict access.
In the future, users will be able to choose on an app-by-app basis which Gaia hub serves their application data.
II. Users own their identities
Users are the sole administer of their own independent and unique identifiers. Within an applications, users must be distinguishable by unique identifiers. The DApp cannot mask or take away a user’s identifier, and a user must be able to bind their identifier to the data they create.
Blockstack DApps anticipate that each user can own one or more IDs. In turn,
these IDs are owned by a private key under the user’s control. The IDs are
acquired through the Blockstack naming system. First time users that log into
the Blockstack application get a free
id.blockstack in the Blockstack namespace.
Blockstack IDs are replicated to all peers via a blockchain, this means Blockstack cannot hide IDs. Blockstack IDs each have a public key assigned to them via the blockchain records that encode their operational history. This public key allows users to bind data to their Blockstack IDs through cryptographic signatures.
III. Users have free choice of clients
Identities and data are application independent. An application cannot be considered a DApp unless it allows users to interact with their identities and data such that the user can later do so via a different DApp.
For example, a user that creates data in client ‘X’ must be able access that data from a different client, ‘Y’, provided the client allows compatible mechanisms. Ultimately, the user has the freedom to write their own client that interacts with their own data.
Blockstack’s APIs and SDKs make it easy to build applications that adhere to this principle. Existing Blockstack applications have this property today simply because they don’t have any irreplaceable server-side logic.
In the future, Blockstack applications must continue to meet the first two principles but need not meet this one. For example, an application could encrypt data in-transit between the application’s client and the user’s chosen storage provider. Unless the app divulges the encryption key to the user, then the user does not have free choice of clients; they can only use clients that the app’s servers choose to interact with.
You’ll notice the Blockstack principles avoid adherence to a particular network topology or architecture. Many DApps have defining characteristics that are implementation-specific rather than expressions of overall DApp design goals. These aspects are mentioned here as specific non-goals of Blockstack applications.
DApps have smart contracts
Decentralized apps pre-date blockchains and smart contracts, and even today there are popular DApps that do not need them. Examples include pre-Microsoft Skype (which was peer-topeer), Mastadon, IRC, and email.
Another word for “smart contract” is “replicated state machine.” Some DApps need each peer to execute the same sequence of operations in order to fulfill their business needs (in which case a smart contract would be appropriate), but many do not.
Blockstack DApps do not use smart contracts at all.
DApps have tokens and/or non-fungible assets
Similar to smart contracts, DApps pre-date tokens and non-fungible assets. While having a crypto token or asset can help incentivize DApp deployment and usage, they are not strictly necessary for their operation.
DApps use a blockchain
Blockchains are a new tool for DApp developers to help coordinate peers, but they are just that – a tool. Sometimes blockchains are the right tool for the job, and sometimes they are not.
DApps serve users
Fundamentally, DApps should serve users by preserving user autonomy. Developers should not profit from abusive features or neglectful designs. Blockstack principles seek to prevent developers from profiting by either (a) building abusive features into DApps like ad networks, or (b) neglecting users by failing to build vital safety features like shadowbans.
Because Blockstack applications allow users to own their identity and data and gives them free choice of clients, any user can simply stop or avoid using bad DApps with near-zero switching cost.
This isn’t to say that DApps can’t be profitable. DApps can still make money for their developers, such as by offering content subscriptions or paid-for add-ons. They can broker with third parties on behalf of their users to watch ads or share data in exchange for tokens.