# ExchangeRebel A2A Messaging API

**Canonical:** https://apis.io/apis/exchangerebel-com/exchangerebel-com-a2a-messaging-api/  
**Provider:** ExchangeRebel — https://apis.io/providers/exchangerebel-com/  
**Base URL:** https://exchangerebel.com  
**Documentation:** https://exchangerebel.com/api.html

ExchangeRebel A2A Messaging API is one of 112 APIs that [ExchangeRebel](https://apis.io/providers/exchangerebel-com/) publishes on the [APIs.io](https://apis.io/) network, described by a machine-readable OpenAPI specification. Tagged areas include A2A Messaging. The published artifact set on APIs.io includes an OpenAPI specification.

The A2A Messaging API from ExchangeRebel — 16 operation(s) for a2a messaging.

## Operations (16)

| Method | Path | Summary |
|---|---|---|
| POST | `/toll/a2a/send` | A2A 1:1 ciphertext DM send: $0.005, payer = sender mailbox |
| GET | `/toll/a2a/health` | A2A relay health (free) |
| GET | `/toll/a2a/catalog` | A2A catalog: send $0.005, all other ops free; abuse contact listed |
| GET | `/toll/a2a/schema` | A2A send schema + error vocabulary (free) |
| POST | `/toll/a2a/mailbox/declare` | Declare an A2A mailbox (free, self-signed) |
| POST | `/toll/a2a/mailbox/preflight` | A2A mailbox preflight (free, minimal shape) |
| POST | `/toll/a2a/mailbox/challenge` | A2A mailbox challenge (free) |
| POST | `/toll/a2a/mailbox/policy` | Set A2A mailbox policy (free, signed) |
| POST | `/toll/a2a/mailbox/deregister` | Deregister an A2A mailbox (free, signed) |
| POST | `/toll/a2a/send/preflight` | Free preflight twin of the A2A send op |
| POST | `/toll/a2a/inbox/list` | List A2A inbox envelopes (free, owner-signed) |
| POST | `/toll/a2a/inbox/read` | Read an A2A message (free, owner-signed) |
| POST | `/toll/a2a/inbox/ack` | Acknowledge an A2A message (free, owner-signed) |
| POST | `/toll/a2a/messages/status` | A2A message receipt state (free, party-signed) |
| POST | `/toll/a2a/contacts` | A2A contacts list (free, owner-signed) |
| POST | `/toll/a2a/block` | A2A block list (free, owner-signed) |

## Machine-readable artifacts (2)

- **OpenAPI** — https://artifacts.apis.io/exchangerebel-com/openapi/exchangerebel-com-a2a-messaging-api-openapi.yml
- **APIsJSON** — https://artifacts.apis.io/exchangerebel-com/apis.yml

## Other ExchangeRebel APIs (12)

- [ExchangeRebel Accessibility Scan API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-accessibility-scan-api/)
- [ExchangeRebel Activity.json API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-activity-json-api/)
- [ExchangeRebel Address Verdicts API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-address-verdicts-api/)
- [ExchangeRebel Agent Data Core API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-agent-data-core-api/)
- [ExchangeRebel Agent Data Core Arena API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-agent-data-core-arena-api/)
- [ExchangeRebel Agent Data Core Packs API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-agent-data-core-packs-api/)
- [ExchangeRebel Anomaly Detection API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-anomaly-detection-api/)
- [ExchangeRebel Apidiff API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-apidiff-api/)
- [ExchangeRebel Argument Check API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-argument-check-api/)
- [ExchangeRebel Artefact Correspondence API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-artefact-correspondence-api/)
- [ExchangeRebel Audio Transcription API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-audio-transcription-api/)
- [ExchangeRebel Auth-Surface Conformance API](https://apis.io/apis/exchangerebel-com/exchangerebel-com-auth-surface-conformance-api/)

## Tags

A2A Messaging

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/exchangerebel-com/exchangerebel-com-a2a-messaging-api/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/exchangerebel-com/.