MainStreet
MainStreet is a US small-business tax-credit and back-office platform that identifies, calculates, and files R&D tax credits alongside a client's CPA. Its service covers qualified research expense (QRE) identification under IRC §41, the IRS four-part test, business-component documentation, Form 6765 preparation (including the mandatory Section G component-level reporting that begins with tax years starting after 31 December 2025), the §41(h) payroll-tax offset for pre-revenue startups, and state R&D credits across 30+ states. Beyond R&D it claims SECURE Act retirement-plan credits, the Small Business Health Care Tax Credit, and the Disabled Access Credit, and it sells adjacent back-office services — entity formation, banking, expense tracking, and bookkeeping and tax filing. MainStreet was founded in 2019 as a venture-backed R&D tax-credit fintech and was acquired by Employer.com in May 2025; the brand now operates as part of that back-office suite. MainStreet ships no public product API, developer portal, or OpenAPI definition — it is an API consumer (payroll data via Finch, document generation via Anvil) rather than an API producer. Its only public machine-readable contract is the OpenID Connect and RFC 8414 discovery pair served by its identity host.
Limited machine-readable signal and partial portal coverage — documentation a human can read, but little a machine or agent can consume without scraping.
API Evangelist profiles MainStreet the way a machine reads it — 4 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 — MainStreet scores 30.3/100 (thin), with a separate agent-readiness read of 9/100 (agent aware). 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 2026-08-17 · rubric v0.11.0
Put this on your own site. The badge is drawn live from MainStreet's current Kin Score — paste it once and it updates itself every time the score is recomputed. It follows your visitor's light or dark setting, and it links back here so anyone who sees it can read the full breakdown.
<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/mainstreet/"
title="MainStreet on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/mainstreet.svg"
alt="MainStreet Kin Score — API readiness rating by API Evangelist" width="150" height="150" loading="lazy">
</a>[](https://providers.apievangelist.com/providers/mainstreet/)<!-- Kin Score · API Evangelist -->
<a href="https://providers.apievangelist.com/providers/mainstreet/"
title="MainStreet on API Evangelist — API profile and Kin Score">
<img src="https://apis.io/badge/mainstreet/card.svg"
alt="MainStreet Kin Score — API readiness rating by API Evangelist" width="340" height="120" loading="lazy">
</a>More shapes, themes and sizes → · Score as JSON · How badges work
How we profile MainStreet
Each block below is one kind of artifact we hold for MainStreet. 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.
MainStreet Identity (OpenID Connect)
The OpenID Connect / OAuth 2.0 authorization surface behind MainStreet sign-in, served from login.mainstreet.com on an Auth0 tenant. It publishes a complete OIDC Discovery 1.0 d...
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.
Scopes 1
OAuth scopes are the vocabulary of least-privilege access. Profiling them shows exactly what an integration — or an agent acting on a user's behalf — is allowed to do.
OAuth scopes governing access to this provider's APIs.
Resources
Every other property we hold for MainStreet — 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 4
Portal, sign-up, and the first successful call
Documentation 1
Reference material describing how the API behaves
Agent Surfaces 2
MCP servers, agent skills, and machine-readable catalogs
Design & Contract 2
Pagination, idempotency, versioning, errors, and events
Access & Security 3
Authentication, authorization, and security posture
Operate 3
Status, limits, changes, and where to get help
Commercial 3
Pricing, plans, and the legal terms of use
Company 2
The organization behind the API
Other 1
Properties that don't map to a standard resource type
← All providers · Data indexed from github.com/api-evangelist/mainstreet · machine-readable index on apis.io
This is an independent, third-party profile of MainStreet, published by API Evangelist. We do not operate, host, resell, or support these APIs, and we are not affiliated with or endorsed by the company unless stated above. Everything here is built from publicly available information — the company's own site, developer portal, documentation, public repositories, and the specifications it publishes for public use. Nothing is obtained by breaching a system, defeating an access control, or using credentials.
The Kin Score and Agent Readiness rating are independently calculated assessments of a company's public API artifacts, scored against a published rubric. They are not certifications, endorsements, security assessments, or audits.
Corrections, re-scores, and removal are free — no partnership or purchase required, and you do not need to justify the request. A removed company is recorded as unrated, never scored zero for having asked. Acknowledgement within one business day; removal within two.
info@apievangelist.com
·
Read the full data-sourcing policy →
On a security or compliance team? Put security in the subject line and
you will get a person, not a form — we will tell you exactly which public URLs this profile was built from.