---
title: "KYE Protocol™ — Build with KYE™ | Runtime Authority API · SDKs · MCP · Connectors · KYE™ Signal Bus™"
description: "Build authority-aware apps with KYE Protocol™. Runtime Authority API, three SDKs (TypeScript / Python / Go), KYE™ MCP Server, Connector Hub™, signed…"
url: https://kyeprotocol.com/build/
lang: en
source: "KYE Protocol"
---

> Build authority-aware apps with KYE Protocol™. Runtime Authority API, three SDKs (TypeScript / Python / Go), KYE™ MCP Server, Connector Hub™, signed…

Build with KYE™

# Build authority-aware apps with KYE™.

KYE Protocol™ is not just a specification — it's a _build surface_. Runtime Authority API, three SDKs, an MCP server, a connector framework, signed webhooks, Decision Maps™, and evidence packs. Add delegated authority, state-aware decisions, and replayable proof to AI agents, payment flows, checkout, wallets, IAM, SIEM, GRC, and enterprise workflows.

Open source

Six surfaces

## Pick the surface that fits your stack.

**Runtime Authority API** Ask whether an entity can act before the action executes. `POST /v1/runtime/authorize` — allow / require\_approval / require\_step\_up / quarantine / deny + reason code + obligations + evidence refs. _view decision endpoint →_ **SDKs** TypeScript, Python, Go. Schema types, validators, decision client, signing helpers, evidence-pack builder, taxonomy resolver, decision-map renderer, webhook verifier. _view SDKs →_ [**KYE™ MCP Server** Expose KYE™ schemas, decisions, Decision Maps™ and evidence packs to MCP-compatible agents and developer tools — while production enforcement stays in the runtime gateway. _explore MCP server →_](https://kyeprotocol.com/mcp/) [**Connector Hub™** Plug KYE™ into payment gateways, checkouts, wallets, IAM, policy engines, SIEM, GRC, agent runtimes, KYC/KYB/KYA. One canonical manifest schema; six families. _view connector hub →_](https://kyeprotocol.com/connectors/) [**KYE™ Signal Bus™** 24 event families, 79 well-known event types, canonical envelope, signed deliveries (HTTPS webhook + SSE / WS + Kafka), idempotent + replayable + dead-letter-safe. _view event reference →_](https://kyeprotocol.com/protocol/#signals) [**Evidence Packs** Generate signed, replayable proof bundles. Public-key-verifiable offline. Bind decisions, audit chain, control mapping, and OSCAL projection in one artefact. _inspect evidence pack →_](https://kyeprotocol.com/compliance-card/)

What you can build

## Six high-use starters — and 15 more.

These are the products with the strongest pull from regulated buyers right now. Each composes from the surfaces above.

- P1 **KYE™ Checkout Guard™** — for merchants and commerce platforms. Detect agent-backed checkout flows and verify whether the agent is allowed to buy _this_ basket from _this_ merchant using _this_ instrument under the customer's limits. Composes: Runtime API + KYE™ Signal Bus™ + Evidence Packs.
- P2 **KYE™ Payment Authority Gateway™** — for banks, issuers, IPGs, MPGs, PSPs, agentic-payment platforms. Verify delegated payment authority before the gateway processes the transaction. Composes: Runtime API + Payments connector + Evidence Packs.
- P3 **KYE™ MCP Server** — for agent developers and internal AI platforms. Expose KYE™ authority objects, schemas, decisions, and evidence to MCP clients safely. Composes: MCP Server + Read-only tools + Gated decision tools.
- P4 **KYE™ CISO Console™** — for security and risk teams. View every agent, credential, capability, delegation, state, and revocation path. Composes: Authority Graph™ + KYE™ Signal Bus™ + Audit chain.
- P5 **KYE™ Evidence Viewer™** — for auditors and regulators. Replay decisions, verify evidence packs offline with public keys, map events to controls. Composes: Evidence Packs + OSCAL projection + Decision Maps™.
- P6 **KYE™ Partner Toolkit™** — for consultants, audit firms, SIs. Run authority mapping, readiness checks, conformance prep, pilot scoping. Composes: Readiness API + Conformance pack + Decision Maps™.

Other strong starters: agent purchasing apps · agent marketplace trust layers · wallet authority consoles · open-banking delegated-authority apps · enterprise service-account authority maps · GRC evidence automation · SIEM authority-signal feeds · certification portals · tool-governance gateways · capability registries · sector profiles for healthcare / custody / telco / federal.

Runtime Authority API

## One call, before the action executes.

The decision endpoint is the single most important surface. Your app asks; KYE™ answers in milliseconds.

```
POST /v1/runtime/authorize
{
  "actor_entity_id":     "kye:entity:agent:shopping_agent_456",
  "principal_entity_id": "kye:entity:person:customer_123",
  "subject":             "kye:capability:payment_action:card_purchase",
  "resource":            { "merchant_id": "M-7104", "amount": 9999, "currency": "GBP" },
  "scope":               { "instrument": "kye:card_token:tok_abc..." },
  "policy_decision_id":  "kye:dec:01HX..."
}

→
{
  "decision":  "allow_with_constraints",
  "reason":    "scope_within_attenuated_authority",
  "obligations": [ { "type": "audit.emit", ... }, { "type": "redaction.required", ... } ],
  "stop_conditions": [ "actor.stop_signal", "delegation.revoked", "scope.attenuated" ],
  "evidence_refs":   [ "kye:evidence-pack:01HX..." ],
  "decision_map_ref": "kye:decision_map:01HX..."
}
```

Eight decision codes are stable across versions: `allow`, `allow_with_constraints`, `require_approval`, `require_step_up`, `require_human_review`, `require_recovery`, `quarantine`, `deny`. Map to your own code-set via the conformance pack.

Three SDKs

## Same surface in TypeScript, Python, and Go.

- **TypeScript** — `npm install @kye/sdk`
- **Python** — `pip install kye-sdk`
- **Go** — `go get` · module path published with the SDK release

Each SDK ships: schema types · local validators · decision client · signing helpers · evidence-pack builder · taxonomy resolver · metadata classifier · graph traversal client · decision-map renderer · webhook verifier · idempotency helper · replay client.

[Developer quickstart →](https://kyeprotocol.com/developers/) [GitHub org](https://github.com/KYE-Protocol)

KYE™ MCP Server

## Make KYE™ available to MCP-compatible agents.

Expose KYE™ schemas, dictionaries, authority checks, Decision Maps™, and evidence packs through a controlled MCP interface — while production enforcement stays in the KYE™ Runtime Gateway™, never in MCP.

**The boundary:** MCP is a developer / agent integration surface. The Runtime Gateway is the enforcement surface. Don't conflate.

[KYE™ MCP Server reference →](https://kyeprotocol.com/mcp/) [Runtime Gateway](https://kyeprotocol.com/protocol/)

Connector Framework

## Plug KYE™ into the systems you already run.

A canonical connector manifest schema, six connector families, and a hub for discovery.

### Payments & commerce

IPG · MPG · payment gateway · checkout · shopping cart · card-token · wallet · open banking · merchant-risk · chargeback / dispute

### AI & agent runtime

MCP · agent runtime · tool gateway · capability registry · model registry · prompt registry · workflow

### Identity & access

OAuth/OIDC · SAML · SCIM · SPIFFE/SPIRE · IAM · PAM · passkey · credential issuer

### Policy & governance

OPA · Cerbos · AWS Cedar · GRC · control mapping · certification · self-audit

### Security & observability

SIEM · SOAR · Splunk · Microsoft Sentinel · Datadog · CloudWatch · Kafka · EventBridge · webhook

### Verification

KYC provider · KYB provider · KYA provider · agent passport · credential verification

[Connector Hub™ →](https://kyeprotocol.com/connectors/) [Composition with adjacent standards](https://kyeprotocol.com/integrations/)

What ships today

## Open source

Every contract below is implementable today — partners and developers integrate without depending on any hosted service.

| Surface | What you get |
| --- | --- |
| Schemas & dictionaries | Every entity / authority / decision / event / connector-manifest schema; reason codes; taxonomies |
| SDKs | TypeScript / Python / Go — schema types, validators, signing helpers, webhook verifier, evidence-pack builder |
| MCP server | Skeleton + read-only tools + decision tools (gated) |
| Connectors | Manifest schema, conformance tests, sample IPG / checkout / MCP connectors, local test harness |
| Reference runtime | KYE™ Reference Gateway™: PEP middleware, embedded ePDP, conformance runner |
| Conformance | 133 black-box fixtures, test vectors |

Adjacent reading

## Where to go next.

[Developer quickstart →](https://kyeprotocol.com/developers/) [MCP server](https://kyeprotocol.com/mcp/) [Connectors](https://kyeprotocol.com/connectors/) [Signal Bus](https://kyeprotocol.com/protocol/#signals) [Partner program](https://kyeprotocol.com/partners/)

## Ready to see your AI agents flagged?

Start in shadow mode. We’ll deliver your first Evidence Pack™ in 4–8 weeks.

[Apply for pilot →](https://kyeprotocol.com/pilot-apply/) [Try the sandbox →](https://kyeprotocol.com/sandbox/demos/)

Canonical KYE™ surfaces referenced on this page: [Authority Graph™](https://kyeprotocol.com/authority-lifecycle/) · [Evidence Pack™](https://kyeprotocol.com/evidence-pack/) · [KYE™ Conformance Pack™](https://kyeprotocol.com/compliance/) · [KYE Protocol™](https://kyeprotocol.com/).