Sozu

Sōzu is an open-source, fast and lightweight HTTP reverse proxy written in Rust, designed for high-performance traffic management in immutable infrastructure environments. It is configurable at runtime through a protobuf-based IPC protocol without requiring restarts, making it ideal for always-up deployments. Sōzu supports TLS termination, load balancing, and dynamic cluster configuration, and is developed by the sozu-proxy open-source organization on GitHub.

Sozu is listed with 3 APIs on the APIs.io network. Tagged areas include Proxy, Reverse Proxy, Load Balancing, Rust, and Open Source.

The Sozu catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

Sozu’s developer surface includes engineering blog, documentation, release notes, and 15 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

25.4/100 emerging ▬ flat Agent 1/100 human only Front door AI 1/6 silent self hosted · AGPL-3.0 Full breakdown ↓
scored 2026-10-23 · rubric v0.25.0 · Show this score on your site →

AccessFreemium

3 APIs

Proxy Reverse Proxy Load Balancing Rust Open Source

Kin Score

Kin Score How this is scored →
scored 2026-10-23 · rubric v0.25.0

Composite quality — 25.4/100 · emerging

Contract Quality 5.0 / 19

Developer Ergonomics 2.0 / 15

Access Clarity 1.2 / 15

Operational Transparency 2.6 / 10

Contract Governance 2.1 / 9

Discoverability 4.7 / 8

Regulatory Posture 1.6 / 15

Open Source Surface 5.0 / 10

Agent readiness — 1/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Open Source Surface applies to this provider. This product is open source and we read its repository directly, so Open Source Surface carries 10 points of the composite. It is scored from what the repository actually publishes — a security policy, a contribution guide, a release history, a code of conduct — read live from the provider rather than inferred from our own catalog pointers. This facet adds; nothing was taken away to make room for it. An open-source project is not excused from the commercial facets, because exemption would strip it of the points it does earn. If we have the wrong repository, or this product is not open source, say so on your provider repo and we will drop the facet rather than have you publish against it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 75 points between them, because both conditional facets apply and carry 25 points together. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 75% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from github.com/api-evangelist/sozu: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Network Edge (CDN, networking, peering, edge compute)	undeclared	-	-	-
Cisco DevNet Ecosystem (builders on Meraki, Catalyst, ISE, ThousandEyes, Splunk)	undeclared	-	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

APIs 3

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

Sozu Command API

The Sozu Command API provides programmatic control of the Sōzu HTTP reverse proxy at runtime. External tools communicate with the Sozu main process through a secure Unix socket ...

Sozu ACME Integration

The Sozu ACME integration automates TLS certificate requests from Let's Encrypt and other ACME-enabled certificate authorities. Originally a standalone tool in the sozu-acme rep...

Sozu Command Futures API

The sozu-command-futures library provides a futures-based async Rust API for configuring the Sōzu HTTP reverse proxy programmatically. It wraps the low-level IPC protocol in an ...

Pricing Plans 1

Published pricing tiers and plan structures.

Sozu Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Sozu Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Sozu Finops

FINOPS

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Sozu Context

8 classes · 16 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs.

Sozu — jsonschema rules

5 rules · 4 warnings 1 info

SPECTRAL

JSON Schema 2

Standalone JSON Schema definitions for this provider's data models.

Sozu Cluster Configuration

6 properties

JSON SCHEMA

Sozu Frontend Configuration

8 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

Sozu Configuration Structure

0 properties

JSON STRUCTURE

Examples 2

Example request and response payloads for these APIs.

Sozu Cluster Example

6 fields

EXAMPLE

Sozu Frontend Example

7 fields

EXAMPLE

Security Posture 1

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

Sozu Domain Security

TLSv1.3 · DNSSEC

SECURITY

Resources

Documentation 2

Reference material describing how the API behaves

ContributionGuide

ContributionGuide

Documentation

Documentation

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

JSONLDContext

JSONLDContext

Vocabulary

Vocabulary

Build 3

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

GitHubRepository

GitHubRepository

Integration Tests

Integration Tests

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 3

Status, limits, changes, and where to get help

RateLimits

RateLimits

IssueTracker

IssueTracker

ReleaseNotes

ReleaseNotes

Commercial 3

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

License

License

Company 3

The organization behind the API

Blog

Blog

LinkedIn

Website

Website

Other 1

Properties that don't map to a standard resource type

Dashboard

Dashboard

Source (apis.yml)

aid: sozu
deliveryModel:
  model: self-hosted
  license: AGPL-3.0
  open_source: true
  commercial: false
  callable_host: false
  label: Self-hosted open source · you run it yourself
  confidence: high
  source:
  - license
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/sozu.png
name: Sozu
description: Sōzu is an open-source, fast and lightweight HTTP reverse proxy written in Rust, designed for high-performance
  traffic management in immutable infrastructure environments. It is configurable at runtime through a protobuf-based IPC
  protocol without requiring restarts, making it ideal for always-up deployments. Sōzu supports TLS termination, load balancing,
  and dynamic cluster configuration, and is developed by the sozu-proxy open-source organization on GitHub.
url: https://raw.githubusercontent.com/api-evangelist/sozu/refs/heads/main/apis.yml
created: '2026-03-27'
modified: '2026-10-06'
specificationVersion: '0.23'
tags:
- Proxy
- Reverse Proxy
- Load Balancing
- Rust
- Open Source
tags_raw:
- Proxy
- Reverse Proxy
- Load Balancing
- Rust
- Open Source
- Open-Source
apis:
- aid: sozu:sozu-command-api
  name: Sozu Command API
  description: The Sozu Command API provides programmatic control of the Sōzu HTTP reverse proxy at runtime. External tools
    communicate with the Sozu main process through a secure Unix socket using a protobuf-based binary protocol (IPC). The
    sozu-command-lib crate ships the protobuf schema, configuration parser, replicated state, channels, and file descriptor
    passing helpers. This enables dynamic cluster configuration, certificate management, and backend routing changes without
    restarts.
  humanURL: https://docs.sozu.io/
  baseURL: https://github.com/sozu-proxy/sozu
  tags:
  - Proxy
  - Command API
  - Protobuf
  - Runtime Configuration
  properties:
  - type: Documentation
    url: https://docs.sozu.io/
  - type: GitHub
    url: https://github.com/sozu-proxy/sozu
  - type: GettingStarted
    url: https://docs.sozu.io/getting-started/
  - type: Configuration
    url: https://github.com/sozu-proxy/sozu/blob/main/doc/configure.md
  - type: How To Use
    url: https://github.com/sozu-proxy/sozu/blob/main/doc/how_to_use.md
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/sozu/refs/heads/main/json-schema/sozu-cluster-schema.json
  - type: JSONSchema
    url: https://raw.githubusercontent.com/api-evangelist/sozu/refs/heads/main/json-schema/sozu-frontend-schema.json
- aid: sozu:sozu-acme-api
  name: Sozu ACME Integration
  description: The Sozu ACME integration automates TLS certificate requests from Let's Encrypt and other ACME-enabled certificate
    authorities. Originally a standalone tool in the sozu-acme repository, it has been integrated directly into the main Sōzu
    binary and is available as a command-line feature.
  humanURL: https://github.com/sozu-proxy/sozu-acme
  tags:
  - TLS
  - Certificates
  - ACME
  - Let's Encrypt
  properties:
  - type: GitHub
    url: https://github.com/sozu-proxy/sozu-acme
- aid: sozu:sozu-command-futures-api
  name: Sozu Command Futures API
  description: The sozu-command-futures library provides a futures-based async Rust API for configuring the Sōzu HTTP reverse
    proxy programmatically. It wraps the low-level IPC protocol in an ergonomic async interface for Rust applications.
  humanURL: https://github.com/sozu-proxy/sozu-command-futures
  tags:
  - Proxy
  - Rust
  - Async
  - Command API
  properties:
  - type: GitHub
    url: https://github.com/sozu-proxy/sozu-command-futures
common:
- type: Plans
  url: plans/sozu-plans-pricing.yml
- type: RateLimits
  url: rate-limits/sozu-rate-limits.yml
- type: FinOps
  url: finops/sozu-finops.yml
- url: https://www.sozu.io/blog/
  type: Blog
- type: IssueTracker
  url: https://github.com/sozu-proxy/sozu/issues
- type: ContributionGuide
  url: https://github.com/sozu-proxy/sozu/blob/main/CONTRIBUTING.md
- type: License
  name: AGPL-3.0
  url: https://github.com/sozu-proxy/sozu/blob/main/LICENSE
- type: DomainSecurity
  url: security/sozu-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/sozu-limited
- type: Website
  url: https://www.sozu.io/
- type: Documentation
  url: https://docs.sozu.io/
- type: GitHubOrganization
  url: https://github.com/sozu-proxy
- type: GitHubRepository
  url: https://github.com/sozu-proxy/sozu
- type: ReleaseNotes
  url: https://github.com/sozu-proxy/sozu/releases
- type: Dashboard
  url: https://github.com/sozu-proxy/dashboard
- type: Integration Tests
  url: https://github.com/sozu-proxy/sozu-integration-tests
- type: JSONLDContext
  url: https://raw.githubusercontent.com/api-evangelist/sozu/refs/heads/main/json-ld/sozu-context.jsonld
- type: Vocabulary
  url: https://raw.githubusercontent.com/api-evangelist/sozu/refs/heads/main/vocabulary/sozu-vocabulary.yml
maintainers:
- FN: API Evangelist
  email: info@apievangelist.com

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