# Services from attester.dev on Zero

> attester.dev serves 11 paid API services for AI agents, indexed by Zero. Each is callable per call with payment handled by Zero.

Canonical page: https://www.zero.xyz/host/attester.dev
Live health (JSON, refreshed every minute): https://www.zero.xyz/host/attester.dev/health.json

## Services

- [MCP Manifest Drift Check](https://www.zero.xyz/c/mcp-manifest-drift-check-74f7069f/llms.txt): $0.01/call via x402. Checks whether an MCP (Model Context Protocol) server's live manifest has drifted from its expected or previously recorded state
- [MCP Manifest Drift Report](https://www.zero.xyz/c/mcp-manifest-drift-report-49488aa3/llms.txt): $0.05/call via x402. Generates a detailed drift report comparing an MCP server's current manifest against a previous or expected state, identifying changes and discrepancies.
- [API-existence Oracle: Symbol Signature Lookup](https://www.zero.xyz/c/api-existence-oracle-symbol-signature-lookup-3714cd86/llms.txt): $0.01/call via x402. Looks up the signature (type/call signature) of a given symbol in a package or codebase.
- [attester.dev Package Version Diff](https://www.zero.xyz/c/attester-dev-package-version-diff-cd328cd0/llms.txt): $0.02/call via x402. Computes and returns the diff between two versions of a software package, highlighting changes in code or metadata.
- [API-existence Oracle: Package Existence Check](https://www.zero.xyz/c/api-existence-oracle-package-existence-check-f9e5bd67/llms.txt): $0.002/call via x402. Checks whether a given software package exists in a registry or ecosystem
- [API-existence Oracle: Symbol Exists](https://www.zero.xyz/c/api-existence-oracle-symbol-exists-6fb8b751/llms.txt): $0.005/call via x402. Checks whether a named symbol (e.g. function, class, or variable) exists in a given codebase or package registry.
- [QA Judge](https://www.zero.xyz/c/qa-judge-e58d9cae/llms.txt): $0.1/call via x402. Evaluates and judges the quality of question-answer pairs or AI outputs, returning a quality assessment score or verdict.
- [SLA Watchtower](https://www.zero.xyz/c/sla-watchtower-9d928368/llms.txt): $0.05/call via x402. Generates an SLA (Service Level Agreement) monitoring report for a target service or endpoint, surfacing uptime, latency, and compliance metrics.
- [Cited Coding Research](https://www.zero.xyz/c/cited-coding-research-18c71b66/llms.txt): $0.1/call via x402. Performs coding research queries and returns answers with cited sources and references.
- [Spend Check](https://www.zero.xyz/c/spend-check-44e0c73d/llms.txt): $0.005/call via x402. Checks whether a specified spend or payment amount meets defined criteria or thresholds via a verification oracle.
- [Verification Oracle](https://www.zero.xyz/c/verification-oracle-293a2fb2/llms.txt): $0.15/call via x402. Verifies or attests claims, facts, or content via an oracle-style POST endpoint with per-call payment.

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

- [Zero catalog index](https://www.zero.xyz/llms.txt)