API-Connected GPTs
Connecting an AI assistant to company data is easy. Making sure it cannot leak confidential records, overwrite live databases, or execute unvetted changes is where most implementations fail. We build zero-trust edge gateways that keep your data intact.
Starting From
10,000 CZK / €420
Entry tier covers API gateway architecture, OpenAPI 3.1 action specification, HMAC/bearer security configuration, and connecting a secure read or proposal workflow to your datastore.
See the Czechia Expat Job Scout, our public working proof demonstrating zero CV storage, HMAC request signing, and bounded discovery queues.
The Real Problem
Prompt rules are not a security perimeter. Instructing an LLM “do not edit column C” or “keep this confidential” is wishful thinking. Prompt injections, hallucinations, or naive user inputs easily bypass conversational guidelines.
The Semantic Stance
Enforce business operations at the gateway. The LLM is never granted generic primitives like updateCell, deleteRow, or executeQuery. It can only call bounded semantic verbs like searchRecords or submitDiscoveryProposal.
What It Proves
Zero-trust AI integrations can be built on lean, cost-effective serverless architecture—Cloudflare Workers, signed webhooks, and audit-logged spreadsheets—without paying for enterprise middleware or risking company data.
Why This Exists
Custom GPTs and conversational agents have become the default interface for internal company workflows: searching directories, querying inventory, screening leads, and retrieving operational documentation.
However, the standard advice—connecting GPT actions directly to no-code webhooks or raw database connectors—creates an immediate security hazard. Prompt instructions cannot reliably protect confidential columns, prevent deletion, or sanitize user input. A single clever prompt injection can trick an assistant into dumping private records or modifying live tables.
Our API-Connected GPT system establishes a zero-trust perimeter between the AI model and your internal databases. Every request is verified by an edge gateway, validated against strict OpenAPI schemas, stripped of personal data, and authenticated with cryptographic signatures. The AI only ever performs the exact business tasks you allow.
The Reality
This is not about building another generic chatbot wrapper or giving an LLM uncontrolled access to your company drive.
It is an engineering pattern that allows your team to use conversational AI safely over real company data without risking data leakage, corrupting master records, or violating GDPR standards.
What it actually does
- OpenAPI 3.1 specification design tailored for custom GPTs, Claude tools, and conversational agents
- Serverless edge gateway (Cloudflare Worker) enforcing authentication, rate limits, and CORS policies
- Cryptographic HMAC-SHA256 request signing between the gateway and internal data backends
- Hard schema validation and prompt injection defenses that reject unauthorized parameters
- Automated PII scrubbing and CV rejection before requests touch internal spreadsheets or databases
- Bounded append-only discovery queues so human operators verify any suggested changes
What a client project can include
- Data sensitivity review and architectural boundary design
- OpenAPI action schema definition and backend endpoint contracts
- Edge API gateway deployment with bearer auth and cryptographic HMAC signing
- Secure connector setup for Google Sheets, Airtable, Notion, or internal SQL databases
- Custom GPT configuration, prompt testing, and guardrail stress-testing
- Operator playbook, audit logging setup, and team handoff documentation
Live Working Proof
Tested on the Czech job market.
We implemented this architecture for the Czechia Expat Job Scout: a custom GPT connected to a 50+ source database through a Cloudflare Worker gateway with zero CV storage and human-reviewed discovery proposals.
Verified Architecture
- Custom GPT with OpenAPI 3.1 action specification
- Cloudflare Worker edge gateway with HMAC-SHA256 signing
- Append-only proposal queue with full audit log
- Zero PII/CV retention and GDPR compliance policy