Harmonic GG website screenshot

Harmonic GG

Harmonic is a highly-configurable, open block-building system for Solana. Validators keep full autonomy over how their blocks are built, choosing their own block builder and scheduling strategy (FBA, FIFO, MREV, or custom) while the block engine streams the constructed block for broadcast. A Remote TPU aggregation layer collects proposals from independent builders in real time, HFT-router style, to raise validator revenue and strengthen network decentralization. Searchers submit atomic transaction bundles over a gRPC interface that is backwards-compatible with Jito's searcher protos, with revert protection, bundle privacy, and tips paid as ordinary priority fees (no protocol cut). Harmonic raised a $6M seed round led by Paradigm.

Harmonic GG publishes 2 APIs on the APIs.io network. Tagged areas include Company, Blockchain, Solana, Block Building, and MEV.

Harmonic GG’s developer surface includes documentation, API reference, getting-started guide, support, signup flow, authentication, sandbox, and 17 more developer resources.

🌐 Visit website 📡 Source on GitHub
29.0/100 emerging ▬ flat Agent 34/100 agent aware Full breakdown ↓
scored 2026-07-27 · rubric v0.5
2 APIs 1 MCP Servers
CompanyBlockchainSolanaBlock BuildingMEVValidatorSearcherInfrastructuregRPCDeFi

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5
Composite quality — 29.0/100 · emerging
Contract Quality 0.0 / 25
Developer Ergonomics 14.3 / 20
Commercial Clarity 4.7 / 20
Operational Transparency 0.7 / 13
Governance 0.0 / 12
Discoverability 9.3 / 10
Agent readiness — 34/100 · agent aware
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 15
MCP Server 12 / 12
Machine-Readable Auth 10 / 10
Idempotency 0 / 9
Stable Error Semantics 8 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 0 / 7
Typed Event Surface 0 / 6
Agent Skills 5 / 5
Well-Known Catalog 0 / 4
Consent & Bot Identity 0 / 3
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/harmonic-gg: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 2

Individual APIs this provider publishes, each with its own machine-readable definition.

Harmonic Searcher API (gRPC)

gRPC bundle-submission interface for searchers. Authenticate with a Solana keypair (challenge-response to Bearer tokens), then submit atomic transaction bundles with revert prot...

Harmonic Validator API (gRPC)

gRPC services the Harmonic validator clients (Salsa/Samba) use to bind to a block builder: subscribe to packet and bundle streams, set the scheduling strategy, discover block en...

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

harmonic-gg-mcp.yml

MCP SERVER

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Harmonic Gg Authentication

challenge-response/bearer · 2 schemes

SECURITY

Harmonic Gg Domain Security

TLSv1.3 · HSTS

SECURITY

Resources

Get Started 4

Portal, sign-up, and the first successful call

DeveloperPortal
DeveloperPortal
 GettingStarted
GettingStarted
 SignUp
SignUp
 Sandbox
Sandbox

Documentation 2

Reference material describing how the API behaves

Documentation
Documentation
 APIReference
APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

LLMsTxt
LLMsTxt
 MCPServer
MCPServer
 AgentSkill
AgentSkill

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions
Conventions
 Conformance
Conformance
 ErrorCatalog
ErrorCatalog
 Lifecycle
Lifecycle
 DataModel
DataModel

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 SourceCode
SourceCode
 Packages
Packages

Access & Security 2

Authentication, authorization, and security posture

Authentication
Authentication
 DomainSecurity
DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support
Support

Commercial 1

Pricing, plans, and the legal terms of use

TermsOfService
TermsOfService

Company 1

The organization behind the API

Website
Website

Other 2

Properties that don't map to a standard resource type

Protobuf
Protobuf
 Protobuf
Protobuf

Source (apis.yml)

apis.yml Raw ↑ 
aid: harmonic-gg
name: Harmonic GG
description: Harmonic is a highly-configurable, open block-building system for Solana. Validators keep full autonomy over
  how their blocks are built, choosing their own block builder and scheduling strategy (FBA, FIFO, MREV, or custom) while
  the block engine streams the constructed block for broadcast. A Remote TPU aggregation layer collects proposals from independent
  builders in real time, HFT-router style, to raise validator revenue and strengthen network decentralization. Searchers submit
  atomic transaction bundles over a gRPC interface that is backwards-compatible with Jito's searcher protos, with revert protection,
  bundle privacy, and tips paid as ordinary priority fees (no protocol cut). Harmonic raised a $6M seed round led by Paradigm.
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
image: https://harmonic.gg/api/og?v=home
url: https://raw.githubusercontent.com/api-evangelist/harmonic-gg/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- paradigm
x-tier: enriched
x-tier-reason: portfolio-lead-enriched
x-sector: blockchain-infrastructure
specificationVersion: '0.20'
created: '2026-07-17'
modified: '2026-07-19'
tags:
- Company
- Blockchain
- Solana
- Block Building
- MEV
- Validator
- Searcher
- Infrastructure
- gRPC
- DeFi
apis:
- name: Harmonic Searcher API (gRPC)
  description: gRPC bundle-submission interface for searchers. Authenticate with a Solana keypair (challenge-response to Bearer
    tokens), then submit atomic transaction bundles with revert protection. Backwards-compatible with Jito's searcher protos;
    tips are priority fees with no protocol cut. Requires a whitelisted searcher pubkey.
  humanURL: https://docs.harmonic.gg/searchers/harmonic-bundles
  baseURL: https://fra.be.harmonic.gg
  tags:
  - Solana
  - MEV
  - Bundles
  - gRPC
  properties:
  - type: Protobuf
    url: grpc/harmonic-gg-searcher-searcher.proto
  - type: Protobuf
    url: grpc/harmonic-gg-searcher-auth.proto
  - type: Protobuf
    url: grpc/harmonic-gg-searcher-bundle.proto
  - type: Authentication
    url: authentication/harmonic-gg-authentication.yml
  - type: ErrorCatalog
    url: errors/harmonic-gg-error-codes.yml
- name: Harmonic Validator API (gRPC)
  description: 'gRPC services the Harmonic validator clients (Salsa/Samba) use to bind to a block builder: subscribe to packet
    and bundle streams, set the scheduling strategy, discover block engine endpoints, report leader windows, and proxy TPU
    traffic via the relayer.'
  humanURL: https://docs.harmonic.gg/run-a-validator/endpoints
  baseURL: https://fra.auction.harmonic.gg
  tags:
  - Solana
  - Validator
  - Block Building
  - gRPC
  properties:
  - type: Protobuf
    url: grpc/harmonic-gg-validator-block_engine.proto
  - type: Protobuf
    url: grpc/harmonic-gg-validator-relayer.proto
  - type: Protobuf
    url: grpc/harmonic-gg-validator-auth.proto
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://harmonic.gg
- type: DeveloperPortal
  url: https://docs.harmonic.gg
- type: Documentation
  url: https://docs.harmonic.gg
- type: APIReference
  url: https://docs.harmonic.gg/searchers/harmonic-bundles
- type: GettingStarted
  url: https://docs.harmonic.gg/run-a-validator/setup
- type: Support
  url: https://discord.com/invite/23GfZkkyAG
- type: GitHubOrganization
  url: https://github.com/harmonic
- type: SourceCode
  url: https://github.com/harmonic/searcher-protos
- type: SignUp
  url: https://form.typeform.com/to/UlJMfbPH
- type: TermsOfService
  url: https://harmonic.gg/terms-and-conditions
- type: Protobuf
  name: Searcher gRPC protos
  url: grpc/harmonic-gg-searcher-searcher.proto
- type: Protobuf
  name: Validator gRPC protos
  url: grpc/harmonic-gg-validator-block_engine.proto
- type: LLMsTxt
  url: llms/harmonic-gg-llms.txt
- type: Authentication
  url: authentication/harmonic-gg-authentication.yml
- type: Sandbox
  url: sandbox/harmonic-gg-sandbox.yml
- type: Conventions
  url: conventions/harmonic-gg-conventions.yml
- type: Conformance
  url: conformance/harmonic-gg-conformance.yml
- type: ErrorCatalog
  url: errors/harmonic-gg-error-codes.yml
- type: Lifecycle
  url: lifecycle/harmonic-gg-lifecycle.yml
- type: DataModel
  url: data-model/harmonic-gg-data-model.yml
- type: MCPServer
  url: mcp/harmonic-gg-mcp.yml
- type: AgentSkill
  url: skills/_index.yml
- type: Packages
  url: packages/harmonic-gg-packages.yml
- type: DomainSecurity
  url: security/harmonic-gg-domain-security.yml
x-enrichment:
  date: '2026-07-19'
  status: backfilled
  pass: local-v1
  note: backfilled from .gitignore signal + verified work evidence