A2A compliance: the full funnel
Every directory shows you a count. We show you what happens at every step from "candidate URL discovered" to "agent actually responds." This is the data nobody else publishes.
The funnel
Real agents, but un-probeable by us
112 of the 6841 candidates returned 401/403 on the agent-card URL. Some of these are stale URLs in our discovery feed that happen to point at credentialed endpoints (CDN paths, admin pages, etc.); others are real agents whose card requires authentication. Both count as "agent exists," but we can't anonymously probe them.
Real agent — but the card requires credentials we don't have. Counts as 'agent exists' but un-anonymously-probeable.
Real agent — but the card requires credentials we don't have. Counts as 'agent exists' but un-anonymously-probeable.
Why most candidates didn't return a valid agent card
4129 of the 6841 candidates failed at the card-fetch step (404, server error, network failure, or returned 200 but with invalid card body). Almost none of this is our bug; it's stale URLs in upstream discovery feeds.
URL has no agent card. These are mostly repos/sites that talk about A2A but don't actually serve /.well-known/agent-card.json.
DNS failed, connect refused, hard timeout, or blocked by safety policy. The host is dead or our crawler couldn't reach it.
Their server is currently broken. Could recover; we re-probe in cold tier.
Non-2xx response on the agent-card URL.
Their server is currently broken. Could recover; we re-probe in cold tier.
Their server is currently broken. Could recover; we re-probe in cold tier.
Provider throttled our crawler — we'll back off and retry.
Non-2xx response on the agent-card URL.
Non-2xx response on the agent-card URL.
Their server is currently broken. Could recover; we re-probe in cold tier.
Non-2xx response on the agent-card URL.
Their server is currently broken. Could recover; we re-probe in cold tier.
Their server is currently broken. Could recover; we re-probe in cold tier.
Their server is currently broken. Could recover; we re-probe in cold tier.
Their server is currently broken. Could recover; we re-probe in cold tier.
Their server is currently broken. Could recover; we re-probe in cold tier.
Of the 5313 valid cards: who actually responds?
Not yet probed: 3175 cards · 59.8%: Indexed but live-probe hasn't run yet (e.g. recently added).
Indexed but live-probe hasn't run yet (e.g. recently added).
Examples
- api.deepbluebase.xyz · api.deepbluebase.xyz
- Exa · exa.ai
- E2B · e2b.dev
- risk-api.life.conway.tech · risk-api.life.conway.tech
- ScreenshotOne · screenshotone.com
Endpoint returned HTTP 200 but the body isn't a valid JSON-RPC 2.0 A2A response.
Examples
- Hive Civilization · Hive Civilization
- Merchant-0 · Merchant-0
- CyMetica AI · Cymetica
- NEXUS Intelligence · NEXUS Intelligence
- BuyWhere · BuyWhere
Agent card is valid but has no .url field — can't be called directly.
Examples
- APIMesh · APIMesh
- microsandbox · microsandbox
- Model Context Protocol · Model Context Protocol
- Atla · Atla
- CoinGecko API · CoinGecko API
Agent endpoint accepts message/send and returns a valid A2A response.
Examples
- Perkoon — Agent Data Layer · Perkoon
- HexNest Machine Reasoning Network · HexNest
- HexNest Machine Reasoning Network · HexNest
- Graph Advocate · PaulieB14
- Torify — Japanese Locale APIs for AI Agents · Torify (operated by Hiroki Sonoda)
Card declares a URL, but that URL returns HTTP 404. Card claim mismatch.
Examples
- AlgoVoi Payment Agent · AlgoVoi
- AlgoVoi Payment Agent · AlgoVoi
- anybrowse · anybrowse
- Botrite by Lattiq · Lattiq LLC
- ThinkNEO Control Plane (MCP Bridge) · ThinkNEO
Agent exists and responds, but requires credentials (401/403). Real but non-anonymous.
Examples
- BidMachine Ad Exchange · BidMachine
- Claw · pi-claw homelab
- SwarmSync Commerce Demo Agent · SwarmSync.AI
- Moirai Agents API · Moirai Labs
- Agent Café
DNS failed, connection refused, or hard timeout — host might be down.
Examples
- The Houstonian Hotel, Club & Spa – Reservations · inHotel
- Hermitage Hotel Prague – Reservations assistant · inHotel
- Adina Hotels – Reservations · inHotel
- Sea Palms Resort – Golf · inHotel
- Vaultfire Agent Hub · Vaultfire Protocol
Endpoint exists but currently returns 5xx errors — likely unhealthy.
Examples
- CeloFX · CeloFX
- Research Agent
- The Data Collector — Web Scraping API · AI Hustler
- Code Agent
- AI Truism · AI Truism
Indexed but live-probe hasn't run yet (e.g. recently added).
Examples
- Mobility Quote Agent · KLO
- inferGONKA · Gonka Network
Are there really this few agents?
Short answer: publicly, yes. For now. A2A v1.0 only hit Linux Foundation in March 2026. The publicly-discoverable surface of the agent web in May 2026 is genuinely in the low hundreds. The rest of the iceberg sits in places our crawler can't reach:
- Enterprise / auth-gated deployments: agents at Salesforce, ServiceNow, SAP, Workday, etc. Real, but listed in their own private directories. Our crawler sees their 401/403 buckets above.
- Agents without
.well-known/agent-card.json: A2A 1.0 allows discovery via the spec's authenticated extended card flow or direct config-handoff between agents. Those are invisible to anonymous probes. - Closed-net deployments: agents running inside corporate VPNs / private VPCs / Cloudflare Access. They use A2A internally but aren't on the public internet.
- Vendor-locked PaaS: Cloud Run / Vercel / Lambda deployments without a discoverability advertisement.
What we DO capture: essentially every public A2A agent listed in registries, awesome-lists, GitHub topics, Certificate Transparency for A2A subdomains, and the official a2aregistry.org. The crawler runs every 6 hours and tiered recrawls keep the working set fresh within 15 minutes for high-quality agents.
Trust is our wedge. Other directories list agents without testing them and end up with 0–4% of "listed" agents actually working (community study). We publish the funnel transparently so you know exactly what you're looking at.