The Problem with AI Today
Every major AI provider operates on the same model: you send your data to their servers, their systems process it, and you receive a response. During that process, your data, such as prompts, documents, code, and personal thoughts, exists in plaintext on infrastructure you don't control. The provider can read it, log it, train on it, or be compelled to hand it over. You have no structural guarantee that your data remains private.
This isn't a hypothetical risk. AI companies have faced data breaches, internal misuse scandals, and regulatory pressure. Even enterprise tiers with contractual privacy promises rely on trust. Trust that the provider follows its own policies, trust that no employee accesses your data, and trust that no court order exposes your conversations. Trust is not a security model.
Cevell exists because we believe there's a better way. One where privacy isn't a policy checkbox, it's a structural property of the system itself.
What Cevell Is
Cevell is a managed cloud service providing a zero-trust AI platform. It provides the same capabilities you'd expect from any modern AI assistant, including natural language conversation, code generation, document analysis, creative writing, and reasoning. But there is one fundamental difference: no one can access your data. Not the company, not the engineers, not the cloud providers. The system is designed so that access is structurally impossible.
At its core, Cevell is a chat-based AI interface backed by large language models (LLMs). You interact with it through a clean, modern web interface. You can create conversations, customize system prompts, manage personas, store archival memories, and use the AI for anything from brainstorming to technical work. It also offers a full REST API for programmatic access, making it suitable for both individual users and developers building on top of it.
What sets Cevell apart is how it handles your data at every stage of the pipeline.
How It Works: The Architecture
Cevell's privacy model is built on three pillars: client-side encryption, sealed execution, and hardware attestation. Here's how each piece fits together:
- Encrypt on device: Your prompts and data are encrypted in your browser before they ever leave your device. The encryption keys are derived from your credentials and never transmitted to Cevell servers.
- Sealed execution: The encrypted data is sent to a sealed runtime environment, an isolated execution container backed by hardware-level protections. The model runs inside this enclave.
- No operator access: Inside the sealed environment, your data is briefly decrypted in memory for inference. No one, including Cevell engineers, can inspect, log, or extract this data. The runtime is structurally isolated.
- Direct return: The model's response is encrypted inside the enclave and returned directly to your browser, where it's decrypted locally. Nothing is stored on Cevell servers. No logs, no copies.
The result: your prompts and AI responses exist in plaintext only in two places. First, in your browser and, briefly, inside a hardware-protected enclave during inference. At no point does any human or external system have access.
Client-Side Encryption in Detail
When you type a message in the Cevell chat, the encryption happens before the network request fires. Your browser generates encryption keys derived from your authentication credentials using industry-standard key derivation functions. These keys never leave your device.
The message payload, including your prompt, any system instructions, conversation history context, and attached files, is encrypted using AES-256-GCM, a symmetric encryption standard used by governments and financial institutions worldwide. The encrypted blob is what gets transmitted over the network. Even if someone intercepts the traffic beyond TLS, they see only ciphertext.
This is fundamentally different from encryption in transit (TLS) that other providers offer. TLS protects data on the wire but decrypts it at the server. Cevell's client-side encryption means the server never sees your plaintext data. It receives an encrypted blob that can only be decrypted inside the sealed execution environment.
Sealed Execution Environments
The sealed execution environment is the heart of Cevell's privacy architecture. It uses Trusted Execution Environments (TEEs), hardware-level isolation mechanisms built into modern processors. Think of it as a locked room inside the CPU that even the operating system and hypervisor cannot peek into.
When your encrypted data arrives at the Cevell infrastructure, it enters a TEE where the decryption key is securely provisioned through a process called remote attestation. The TEE proves its identity and integrity to a verification service before receiving the key material needed to decrypt your data. This attestation is cryptographically verifiable, meaning you can confirm that the code running inside the enclave is exactly what Cevell publishes in its publicly auditable repository.
Inside the TEE, the LLM performs inference on your decrypted prompt. The response is encrypted before it leaves the enclave. Memory used during inference is wiped. No data persists after the request completes.
Key properties of the sealed environment:
- No shared runtime: your inference runs in isolation
- No inspection layer: no debugging ports, no memory dumps
- No persistence: data is wiped after each request
- Attestation-verified: the running code is cryptographically proven
- Publicly auditable: the enclave code is available for public audit
What You Can Do with Cevell
Cevell is a full-featured AI platform. Privacy doesn't come at the cost of capability. Here's what's available:
- Chat Interface: A modern, responsive chat UI with conversation management, markdown rendering, code syntax highlighting, and streaming responses. Supports multiple conversations with full history.
- Customizable System Prompts: A modular prompt builder lets you control exactly what instructions the AI receives. Configure persona behavior, response preferences, reasoning modes, and custom instruction blocks, all assembled automatically on each message send.
- Personas & Profiles: Create and switch between multiple AI personas, each with their own system prompt and personality. Your user profile is injected into the prompt for personalized responses.
- Archival Memory: Store persistent memories that the AI recalls across conversations. Memories are fetched from your personal vault and included in the system prompt, giving the AI long-term context about you.
- REST API: Full programmatic access via API keys. Create keys, monitor usage, and integrate Cevell into your own applications. The API supports the same models and privacy guarantees as the web interface.
- Multiple Models: Access to a curated selection of LLMs, all running through Cevell's sealed infrastructure. Select different models for different tasks, each with the same zero-trust privacy guarantees.
- Bring Your Own Model (BYOM): We fully support BYOM and custom model deployment requests, allowing you to run your preferred models securely within our confidential computing environment.
The Threat Model
Cevell is designed around the principle of assume compromise. The system is architected so that even if Cevell's servers, network, or personnel are compromised, your data remains protected. Here's what the threat model covers:
- Malicious insider: No employee has access to decrypted user data. The sealed environment prevents inspection even with root access to the host.
- Server compromise: Encrypted blobs on the server are useless without keys that only exist inside the TEE. Compromising the server yields only ciphertext.
- Network interception: Data is encrypted client-side before TLS. Even with a TLS MITM attack, the attacker sees only AES-256-GCM ciphertext.
- Legal compulsion: Cevell cannot produce plaintext data in response to subpoenas or court orders because it structurally does not possess decryption keys.
- Training on user data: Data is never stored or logged. There is no mechanism to feed user conversations into model training pipelines.
Who Cevell Is For
Cevell serves anyone who needs AI capabilities without surrendering control over their data:
- Enterprises: Run sensitive workflows like legal analysis, financial modeling, or HR processes, without exposing client or employee data to third-party AI providers.
- Developers: Build AI-powered features into applications with a privacy-first API. Your users' data stays protected end-to-end.
- Compliance teams: Meet GDPR, HIPAA, SOC 2, and other regulatory requirements without workarounds. The architecture provides structural compliance, not policy-based compliance.
- Security professionals: Analyze code, review configurations, and discuss vulnerabilities with AI, without the data ever leaving a controlled environment.
- Individuals: Use AI for personal journaling, health questions, financial planning, or anything else you wouldn't want a company to read.
Technical Stack
For those interested in the engineering details, here's an overview of the technologies powering Cevell:
| Layer |
Technology |
| Frontend | React + TypeScript, Vite, Framer Motion, Tailwind CSS |
| Authentication | Supabase Auth with Google OAuth, session-based JWT |
| Database | Supabase (PostgreSQL) with Row-Level Security (RLS) |
| Client Encryption | AES-256-GCM, browser-native Web Crypto API |
| Sealed Runtime | Trusted Execution Environments (TEE) with hardware attestation |
| API Gateway | Custom gateway with rate limiting, API key management, credit-based billing |
| LLM Inference | Multiple model support via internal routing to sealed execution endpoints |
| Deployment | Vercel (frontend), containerized backend infrastructure |
Verification & Transparency
Privacy claims without verifiability are just marketing. Cevell is committed to transparency.
The sealed enclave code is publicly auditable. Anyone can audit the code that runs inside the TEE and verify that it does exactly what we claim, decrypt, run inference, encrypt the response, and wipe memory. No hidden logging, no data exfiltration, no backdoors.
Remote attestation provides cryptographic proof that the code running in production matches the published source. You don't have to trust Cevell's word. You can verify it mathematically through attestation reports signed by the hardware manufacturer.
Cevell maintains a public bug disclosure and bounty program. Security researchers are encouraged to audit the system and report vulnerabilities. Confirmed findings are disclosed publicly and remediated transparently.
The Bottom Line
Cevell doesn't ask you to trust it. It's built so trust isn't necessary. The architecture ensures that your data remains yours, not through policies or promises, but through cryptographic enforcement and hardware isolation.
If you value your privacy and want access to powerful AI without compromise, Cevell is built for you. No ads. No trackers. No data harvesting. Just a sealed, verifiable execution environment where your words remain yours.