H-Series: Infrastructure for the agentic economy
The H-Series is a family of products built on Hedera Consensus Service. Each answers one question an autonomous agent has to settle before it can be trusted with real work. Every product runs standalone. Together they form one verifiable lifecycle.
One substrate underneath all of it
The products compose without bespoke integration because they share the same foundations. Adopt one and the next is familiar.
HCS, not a private database
Every product writes its authoritative records to a Hedera Consensus Service topic, then derives a local index. Any product rebuilds its full state by replaying from a mirror node.
CAIP-10 across every chain
Agents, callers, and owners are addressed by chain-agnostic CAIP-10 identifiers. The same identity string means the same actor in every product.
TIP-712 structured signing
No product signs a bare payload. Every registration, grant, receipt, and envelope is a typed document signed by its owner and verifiable from the public record.
x402, priced in USD cents
Paid actions use the x402 micropayment standard. USD cents is canonical; per-chain stablecoin amounts derive from it. The same facilitator code is reused across products.
Four products, one family
Each solves one problem on its own. The composition seams are opt-in, never required.
H-Index
Where is the agent or service, and what can it do?
A capability registry for the agentic economy. Publishers register MCP servers and API endpoints, gated by a one-time micropayment, with an optional signed snapshot of the server's tool manifest. Discovery is free, served from a local index with semantic search.
Standalone: A working, paid registry agents query directly. It is also the shared address book every other product resolves identities against.
H-Seal
Can you prove what was asked, and what was done?
Cryptographic proof of execution. A receipt anchors hashes of the request and response with identities and timestamps; payloads stay off-chain. The symmetric request envelope (the notary) anchors the ask before the call, so envelope and receipt bracket a full interaction.
Standalone: Any MCP service, API, or agent-to-agent call can anchor receipts without being listed anywhere. An SDK lets a provider sign its half of a receipt.
H-Grant
What is this agent allowed to do with real accounts?
Holds the credentials an agent needs in a sealed enclave and releases them only inside a policy the owner signs. The agent never sees the raw secret; a broker checks the active grant, executes the call, and anchors every release or refusal. A signed revocation is the freeze button.
Standalone: Gates credentials for any agent against any upstream API. The corporate-card model for software agents.
H-Relay
How does the message actually reach the agent?
The communication plane. One service, three modes: Inbox (point-to-point store-and-forward), Broadcast (one-to-many liveness), and Relay (fetch-through context proxy). All route against H-Index as the address book.
Standalone: An agent messaging and liveness service addressed by identity. Optionally calls H-Seal to stamp a delivery with proof.
Reach the whole suite from one place
Beyond the per-product HTTP APIs, the suite ships developer surfaces so agents and providers integrate once, not five times.
H-Series MCP server
LiveA single Model Context Protocol server exposes the suite's actions as tools, so an agent can discover, authorize, reach, and prove through one connection instead of integrating each product separately.
H-Seal SDK
BuiltAn installable library for the provider side of a receipt. A service that receives a call uses it to sign its half of the H-Seal receipt, so both caller and provider attest to the same interaction.
Run end to end, they trace one interaction
The thread through every step is the same identity, the same signing, the same on-chain timestamps. No step trusts another's private database; each verifies the prior step's public record.
- 1 DiscoverH-Indexwhere
- 2 AuthorizeH-Grantwhat's allowed
- 3 ReachH-Relayhow it arrives
- 4 Prove requestH-Sealwhat was asked
- 5 Prove resultH-Sealwhat was done
Standalone first. Ecosystem when you want it.
The H-Series is deliberately not a monolith. A service that needs to be findable buys H-Index. A workflow that needs an audit trail buys H-Seal. A security team blocked on handing agents root credentials buys H-Grant. Because they share one substrate, adopting a second product is additive, not a migration.