Core Concepts
The SAND stack is built on foundational ideas that distinguish it from the centralized web. Understanding these concepts reveals how the protocols work together to create a user-centric internet.
Why This Matters
The current web has a problem:
Problems:
- Data scattered across platforms you don't control
- Identity tied to each platform separately
- Platforms can ban you, change terms, or shut down
- Your data trains their AI, serves their ads
- No portability — leaving means losing everything
The decentralized web inverts this:
Benefits:
- One identity, portable everywhere
- Data in one place you control
- Apps request access, you grant it
- Switch apps without losing anything
- Your AI agents work for you
The Core Ideas
Data Sovereignty
Your data belongs to you. Not to platforms, not to advertisers, not to algorithms.
| Web 2.0 | Decentralized Web |
|---|---|
| Platform stores your posts | You store your posts |
| Platform decides who sees them | You decide who sees them |
| Platform can delete them | Only you can delete them |
| Leaving = losing data | Take your data anywhere |
How it works: Solid gives you a "pod" — a personal data store at a URL you control. Nostr broadcasts signed events to relays. In both cases, the data is yours.
Federation
Instead of one giant server controlled by one company, federated systems connect many servers run by many people.
Why it matters: No single point of failure. No single entity can censor everyone. You can move to another server and keep your connections.
Decentralized Identity
Your identity shouldn't depend on any single company. DIDs let you prove who you are without a middleman.
| Traditional | Decentralized |
|---|---|
| @username on Platform X | did:web:yoursite.com |
| Platform verifies you | Cryptographic proof |
| Platform can ban you | No one controls your DID |
| Different identity per site | Same identity everywhere |
Key methods:
did:key— Identity from a cryptographic keydid:web— Identity from a domain you controldid:nostr— Identity from a Nostr keypair
Linked Data
Data that connects to other data. Every piece of information has a URL and can link to other information.
Why it matters: Data becomes interoperable. Alice's profile can link to Bob's without them being on the same platform.
Local-First
Your apps and data work offline. The cloud is optional. Your device is the source of truth.
| Cloud-First | Local-First |
|---|---|
| Data lives on server | Data lives on device |
| Offline = broken | Offline = works fine |
| Server down = stuck | Server down = sync later |
| Latency to server | Instant local access |
How it applies:
- Solid pods can be local
- Nostr clients cache events locally
- CRDTs enable conflict-free sync
The Agentic Web
AI agents that work for you, not for platforms. Agents that can read your data, act on your behalf, and answer to you.
The shift: When you control your data, AI agents can work with it on your terms. They can manage your Solid pod, post to Nostr, interact with federated services — all under your direction.
How Concepts Map to Protocols
| Concept | Solid | ActivityPub | Nostr | DIDs |
|---|---|---|---|---|
| Data Sovereignty | Pods store your data | Limited — server stores | Events signed by you | N/A |
| Federation | Pods can federate | Core architecture | Relay network | Resolvers federate |
| Decentralized ID | WebID | Actor URLs | npub/nsec keypairs | Native |
| Linked Data | RDF/JSON-LD native | JSON-LD objects | Tags link events | DID Documents |
| Local-First | Local pod option | Limited | Client-side caching | Local resolution |
| Agentic | Apps read pods | Bots/automation | AI posting | Agent DIDs |
Real-World Examples
Example 1: Social Media
Web 2.0: You post on Twitter. Twitter owns the post. If banned, you lose everything.
SAND Stack: You post a Nostr event signed with your key. It propagates to relays. Your identity is your keypair. Any client can display it. You can switch clients without losing followers.
Example 2: Personal Website
Web 2.0: Your data is in Notion, Google Docs, Dropbox — scattered.
SAND Stack: Your Solid pod holds documents, notes, contacts. Apps read from the pod with your permission. Switch apps freely; data stays in your pod.
Example 3: AI Assistant
Web 2.0: ChatGPT doesn't know your preferences unless you tell it each time.
SAND Stack: Your AI agent has permission to read your pod. It knows your calendar, contacts, preferences. It can draft posts to Nostr, schedule events, manage permissions — all with your approval.
The Stack Together
Each protocol addresses different needs:
- Solid — Structured personal data with fine-grained access control
- ActivityPub — Federated social networking between servers
- Nostr — Censorship-resistant public messaging
- DIDs — Portable, self-sovereign identity
They can work together:
- Use a DID to authenticate to your Solid pod
- Have your Nostr posts reference data in your pod
- Bridge ActivityPub and Nostr for cross-protocol social
Comparison: Web 2.0 vs SAND
| Aspect | Web 2.0 | SAND Stack |
|---|---|---|
| Data location | Platform servers | Your pod/device |
| Data ownership | Platform's terms | You own it |
| Identity | Username per platform | Portable DID/keys |
| Interoperability | APIs if allowed | Built-in via protocols |
| Censorship | Platform decides | You decide (mostly) |
| Vendor lock-in | High | Low |
| AI training | Your data used freely | You control access |
| Switching cost | Lose everything | Take data with you |
Getting Started
Each concept has a dedicated page with deeper exploration:
- Data Sovereignty — The foundation: your data, your rules
- Federation — How servers cooperate without centralization
- Decentralized Identity — Portable identity across the web
- Linked Data — Making data connect and interoperate
- Local-First — Offline-capable, resilient applications
- The Agentic Web — AI that serves you, not platforms
Or jump to the Architecture page to see how everything fits together technically.