Cumulus Labs
Cumulus Labs is a Y Combinator (W26) company building a unified inference platform for production AI. Cumulus consolidates the eight subsystems teams normally assemble from separate vendors — an OpenAI-compatible gateway, a per-workflow router, a layered prompt/KV cache, request-level observability, continuous shadow evaluation, one-click LoRA fine-tuning, custom open-weight hosting, and the proprietary Ion inference engine running on NVIDIA Grace and Blackwell GPUs — behind a single OpenAI-compatible API at api.cumuluslabs.io/v1. Ion's custom attention kernels deliver 30-50% more throughput than stock vLLM and SGLang, and the gateway is a drop-in replacement for the OpenAI, Anthropic, LangChain, LlamaIndex, and Vercel AI SDKs — change one line of configuration and keep your existing code.
More than an index entry, but the surface is still mostly links rather than artifacts — the cohort most likely to move a full band from modest, well-targeted work.
API Evangelist profiles Cumulus Labs the way a machine reads it — 3 machine-readable artifacts across 1 API, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Cumulus Labs scores 24.6/100 (emerging), with a separate agent-readiness read of 10/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
Kin Score
How this is scored →scored 2026-07-27 · rubric v0.5
How we profile Cumulus Labs
Each block below is one kind of artifact we hold for Cumulus Labs. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 1
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
Cumulus Inference Gateway
OpenAI-compatible HTTP inference gateway. One client works against every upstream provider; per-workflow routing rules pick the model, provider, and infrastructure, with a layer...
Security Posture 2
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Cumulus Labs — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 2
Portal, sign-up, and the first successful call
Documentation 2
Reference material describing how the API behaves
Agent Surfaces 1
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 3
Pagination, idempotency, versioning, errors, and events
Build 1
SDKs, sample code, and the tooling you integrate with
Access & Security 2
Authentication, authorization, and security posture
Operate 1
Status, limits, changes, and where to get help
Commercial 2
Pricing, plans, and the legal terms of use
Company 4
The organization behind the API
← All providers · Data indexed from github.com/api-evangelist/cumulus-labs · machine-readable index on apis.io