Standards
HCS Standards
Discover the comprehensive collection of Hashgraph Consensus Standards (HCS) authored by Hashgraph Online — enabling interoperable agent communication, registries, content inscription, and application composition.
HCS-1: File Management
The HCS-1 standard provides a systematic approach to encode, chunk, upload, retrieve, and reassemble file data for applications using Hedera Consensus Service (HCS). This process is agnostic of the implementation details, focusing on the JSON structure and the use of a Topic ID for efficient data management.
HCS-2: Topic Registries
The HCS-2 standard defines advanced topic registries for Hedera Consensus Service, enabling structured data organization and retrieval.
HCS-3: Recursion
The HCS-3 standard defines a method for implementing recursion within Hedera Consensus Service, enabling more complex data structures and relationships.
HCS-4 — HCS Standardization Process
Defines the lifecycle, roles, criteria, and repository workflow for proposing, reviewing, approving, publishing, and maintaining Hiero Consensus Standards (HCS).
HCS-5: Hashinals
This specification provides a standard way to "inscribe" Hashinals utilizing the Hedera Consensus and Hedera Token Services. Hashinals borrow many ideas from Ordinal theory on Bitcoin, and apply them in a more efficient, and scalable way for the Hedera Hashgraph.
HCS-6: Dynamic Hashinals
The HCS-6 standard defines a framework for creating dynamic Hashinals on the Hedera Hashgraph, enabling interactive and updatable on-chain assets.
HCS-7: Smart Hashinals
HCS-7 enables dynamic NFTs (Hashinals) whose metadata automatically updates based on smart contract state using a micro-DSL for deterministic topic selection and WASM processing. This standard supports creating reactive, state-dependent NFTs without requiring additional transactions for updates.
HCS-8
The HCS-8 standard introduces a framework to use Hedera Consensus Service (HCS) topics to manage polls.
HCS-9: Poll Metadata
HCS-9: Poll Metadata for HCS-9 Poll Metadata Schema.
HCS-10
The HCS-10 standard establishes a framework for AI agents to autonomously communicate using the Hedera Consensus Service (HCS). This includes creating accounts, registering agents in a registry, and securely managing AI-to-AI and human-to-AI communication channels. HCS-10 provides scalable, secure, and decentralized communication solutions while leveraging existing Hedera standards.
HCS-11: Profile Metadata
The HCS-11 standard defines a systematic approach for managing profiles on the Hedera Hashgraph through account memos, enabling rich identity management for individuals and AI agents.
HCS-12
HCS-13: Schema Registry
This specification provides a standard way to define, register, and reference schemas for data validation and structure in the Hedera ecosystem, enabling type-safe data exchange and improved interoperability.
HCS-14 - Universal Agent ID Standard
The HCS-14 standard provides a systematic approach for generating globally unique identifiers for AI agents that work across both web2 and web3 environments.
HCS-15
The HCS-15 standard provides a dynamic ability for account holders to create multiple instances of their accounts that use the same private key.
HCS-16
The HCS‑16 standard defines rules and recommended practices for multi‑party "Flora" accounts, enabling cohesive coordination, shared escrow, and state consensus between two or more agents that already expose HCS‑11 and HCS‑15 profiles.
HCS-17
HCS-17 defines the methodology for calculating state hashes of accounts and decentralized formations on Hiero to ensure consistent, auditable, and tamper-proof state verification for distributed AI networks.
HCS-18
The HCS-18 standard defines a discovery and formation protocol for Floras, enabling autonomous Petal accounts to find each other and establish multi-party entities through an open broadcast mechanism.
HCS‑19 Standard: AI Agent Privacy Compliance
"The HCS‑19 standard defines a comprehensive, ISO/IEC TS 27560‑aligned framework
HCS-20
HCS-20 is a new proposed standard (created by @TurtelMoonCC & @HGraphPunks) that defines how points can be managed and audited on the Hedera Hashgraph. It is inspired by the BRC-20 protocol on Ordinals and has extended the functionality to auditable points in addition to introducing inscriptions on Hedera / Hashinals.
HCS-21
Defines a platform-agnostic adapter registry that packages decentralized adapters, their manifests, and their consensus context for distributed appnets (Floras).
HCS-26: Decentralized Agent Skills Registry
Standard for registering versioned agent skills on HCS using HCS-2 registries and HCS-1 manifests.