ThetaData

ThetaData is a developer-first US market data vendor founded in 2022 by Bailey Danseglio, selling real-time and historical options, stocks, indices, and interest-rates data with unfiltered tick-level trades, quotes, and Greeks. Delivery is self-serve via the Theta Terminal, a local Java application that authenticates with an API key or account credentials and exposes a local REST API (127.0.0.1:25503/v3), a WebSocket streaming API (127.0.0.1:25520), and an MCP server, backed by a published OpenAPI 3.1 spec, Python library, flat files, and tiered monthly subscriptions.

ThetaData publishes 6 APIs on the APIs.io network, including Streaming WebSocket API, Calendar API, Index API, and 3 more. Tagged areas include Financial, Market Data, Options, Stocks, and Indices.

The ThetaData catalog on APIs.io includes 1 event-driven AsyncAPI specification.

ThetaData’s developer surface includes developer portal, documentation, engineering blog, pricing, signup flow, support, getting-started guide, and 36 more developer resources.

🌐 Visit website 📡 Source on GitHub

62.4/100 strong ▬ flat Agent 32/100 agent ready saas Full breakdown ↓
scored 2026-09-06 · rubric v0.19.0

AccessFreemiumFree trial⚡ Free to try

1 APIs

Financial Market Data Options Stocks Indices Real-Time Historical Data Trading

Kin Score

Kin Score How this is scored →
scored 2026-09-06 · rubric v0.19.0

Composite quality — 62.4/100 · strong

Contract Quality 11.1 / 21

Developer Ergonomics 11.8 / 17

Access Clarity 13.0 / 17

Operational Transparency 8.7 / 11

Contract Governance 0.5 / 10

Discoverability 5.8 / 9

Regulatory Posture 7.8 / 15

Agent readiness — 32/100 · agent ready

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 4 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Regulatory Posture applies to this provider. Its tags matched the Securities & Market Data 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.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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/thetadata: 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 →

APIs 7

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

Open Collections 13

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

Rate Limits 1

Documented rate limits and quota policies.

Get Started 4

Portal, sign-up, and the first successful call

Portal

SignUp

GettingStarted

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

WellKnown

WellKnown

LLMsTxt

LLMsTxt

AgentSkill

AgentSkill

Design & Contract 7

Pagination, idempotency, versioning, errors, and events

Conformance

ErrorCatalog

Lifecycle

Conventions

Idempotency

Components

DataModel

Scroll for all 7

Build 5

SDKs, sample code, and the tooling you integrate with

PostmanWorkspace

PostmanWorkspace

GitHubOrganization

SampleData

Packages

SDKs

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 6

Status, limits, changes, and where to get help

Support

StatusPage

Roadmap

Deprecation

ChangeLog

RateLimits

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 3

The organization behind the API

Website

Website

Blog

Blog

LinkedIn

Other 7

Properties that don't map to a standard resource type

Overlay

Overlay

Overlay

Overlay

Overlay

Overlay

Overlay

Scroll for all 7

Source (apis.yml)

aid: thetadata
url: https://raw.githubusercontent.com/api-evangelist/thetadata/refs/heads/main/apis.yml
name: ThetaData
kind: company
description: ThetaData is a developer-first US market data vendor founded in 2022 by Bailey Danseglio, selling real-time and
  historical options, stocks, indices, and interest-rates data with unfiltered tick-level trades, quotes, and Greeks. Delivery
  is self-serve via the Theta Terminal, a local Java application that authenticates with an API key or account credentials
  and exposes a local REST API (127.0.0.1:25503/v3), a WebSocket streaming API (127.0.0.1:25520), and an MCP server, backed
  by a published OpenAPI 3.1 spec, Python library, flat files, and tiered monthly subscriptions.
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: self-service
  trial: true
  try_now: true
  public: true
  label: Freemium, self-service signup
  confidence: high
  source:
  - https://thetadata.net/pricing
  - https://docs.thetadata.us/Articles/Getting-Started/Subscriptions.html
  - https://docs.thetadata.us/Articles/Getting-Started/Sample-Data.html
  generated: '2026-07-22'
  method: searched
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/thetadata.png
tags:
- Financial
- Market Data
- Options
- Stocks
- Indices
- Real-Time
- Historical Data
- Trading
created: '2026-07-21'
modified: '2026-07-22'
specificationVersion: '0.23'
apis:
- aid: thetadata:thetadata-streaming-websocket-api
  name: ThetaData Streaming WebSocket API
  tags:
  - Streaming
  - WebSocket
  - Trades
  - Quotes
  - Real-Time
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://docs.thetadata.us/Streaming/Getting-Started.html
  baseURL: ws://127.0.0.1:25520/v1/events
  properties:
  - url: https://docs.thetadata.us/Streaming/Getting-Started.html
    type: Documentation
  - type: AsyncAPI
    url: asyncapi/thetadata-streaming-asyncapi.yml
  description: JSON WebSocket streaming of US stock trade/quote, options trade/quote, and index price streams, served locally
    by the Theta Terminal at ws://127.0.0.1:25520/v1/events. Requires a paid subscription with streaming permissions; a single
    connection per user is permitted, with CONNECTED/DISCONNECTED status headers and QUOTE/TRADE/STATUS message types.
- aid: thetadata:thetadata-mcp-server
  name: ThetaData MCP Server
  tags:
  - MCP
  - Agents
  - SSE
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  humanURL: https://docs.thetadata.us/Mcp/Getting-Started.html
  baseURL: http://127.0.0.1:25503/mcp/sse
  properties:
  - url: https://docs.thetadata.us/Mcp/Getting-Started.html
    type: Documentation
  - type: X-MCPServerCandidate
    url: mcp/thetadata-mcp.yml
    note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list
      derived from the published API contracts, not an existing server. The scorer already read the manifest and reported
      mcp_server correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
  - type: ToolCrosswalk
    url: mcp/thetadata-tool-crosswalk.yml
  description: Model Context Protocol server built into Theta Terminal v3, exposing the full v3 API to LLM CLIs (documented
    for Claude CLI and Gemini CLI) over SSE at http://127.0.0.1:25503/mcp/sse. Requires the terminal running locally and a
    valid ThetaData subscription.
- aid: thetadata:thetadata-calendar-api
  name: ThetaData Calendar API
  description: The Calendar API from ThetaData — 3 operation(s) for calendar.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Calendar
  properties:
  - type: OpenAPI
    url: openapi/thetadata-calendar-api-openapi.yml
  - type: Documentation
    url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
  - type: APIReference
    url: https://docs.thetadata.us/operations/stock_list_symbols.html
  - type: Overlay
    url: overlays/thetadata-calendar-api-overlay.yaml
- aid: thetadata:thetadata-index-api
  name: ThetaData Index API
  description: The Index API from ThetaData — 10 operation(s) for index.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Index
  properties:
  - type: OpenAPI
    url: openapi/thetadata-index-api-openapi.yml
  - type: Documentation
    url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
  - type: APIReference
    url: https://docs.thetadata.us/operations/stock_list_symbols.html
  - type: Overlay
    url: overlays/thetadata-index-api-overlay.yaml
- aid: thetadata:thetadata-interest-rate-api
  name: ThetaData Interest Rate API
  description: The Interest Rate API from ThetaData — 1 operation(s) for interest rate.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Interest Rate
  properties:
  - type: OpenAPI
    url: openapi/thetadata-interest-rate-api-openapi.yml
  - type: Documentation
    url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
  - type: APIReference
    url: https://docs.thetadata.us/operations/stock_list_symbols.html
  - type: Overlay
    url: overlays/thetadata-interest-rate-api-overlay.yaml
- aid: thetadata:thetadata-option-api
  name: ThetaData Option API
  description: The Option API from ThetaData — 37 operation(s) for option.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Option
  properties:
  - type: OpenAPI
    url: openapi/thetadata-option-api-openapi.yml
  - type: Documentation
    url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
  - type: APIReference
    url: https://docs.thetadata.us/operations/stock_list_symbols.html
  - type: Overlay
    url: overlays/thetadata-option-api-overlay.yaml
- aid: thetadata:thetadata-stock-api
  name: ThetaData Stock API
  description: The Stock API from ThetaData — 15 operation(s) for stock.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Stock
  properties:
  - type: OpenAPI
    url: openapi/thetadata-stock-api-openapi.yml
  - type: Documentation
    url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
  - type: APIReference
    url: https://docs.thetadata.us/operations/stock_list_symbols.html
  - type: Overlay
    url: overlays/thetadata-stock-api-overlay.yaml
common:
- type: Overlay
  url: overlays/thetadata-at-time-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-flatfile-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-history-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-list-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-single-day-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-snapshot-api-overlay.yaml
- type: Overlay
  url: overlays/thetadata-year-api-overlay.yaml
- type: PostmanWorkspace
  url: https://www.postman.com/kinlaneapi/thetadata/overview
- type: DomainSecurity
  url: security/thetadata-domain-security.yml
- type: Website
  url: https://thetadata.net/
- type: Portal
  url: https://thetadata.net/portal
- type: Documentation
  url: https://docs.thetadata.us/
- type: Blog
  url: https://thetadata.net/blog
- type: Pricing
  url: https://thetadata.net/pricing
- type: SignUp
  url: https://thetadata.net/signup
- type: TermsOfService
  url: https://thetadata.net/terms-and-conditions
- type: PrivacyPolicy
  url: https://thetadata.net/privacy-policy
- type: Support
  url: https://discord.thetadata.us/
- type: StatusPage
  url: https://thetadata.statuspage.io/
- type: LinkedIn
  url: https://www.linkedin.com/company/axiomx-theta-data
- type: GettingStarted
  url: https://docs.thetadata.us/Articles/Getting-Started/Getting-Started.html
- type: APIReference
  url: https://docs.thetadata.us/
- type: Roadmap
  url: https://thetadata.net/roadmap
- type: GitHubOrganization
  url: https://github.com/AXIOMXLLC
- type: SampleData
  url: https://docs.thetadata.us/Articles/Getting-Started/Sample-Data.html
- type: Packages
  url: packages/thetadata-packages.yml
- type: SDKs
  url: packages/thetadata-packages.yml
- type: WellKnown
  url: well-known/thetadata-well-known.yml
- type: LLMsTxt
  url: llms/thetadata-llms.txt
- type: Conformance
  url: conformance/thetadata-conformance.yml
- type: ErrorCatalog
  url: errors/thetadata-problem-types.yml
- type: Lifecycle
  url: lifecycle/thetadata-lifecycle.yml
- type: Deprecation
  url: https://docs.thetadata.us/Articles/Getting-Started/v2-migration-guide.html
- type: Authentication
  url: authentication/thetadata-authentication.yml
- type: Sandbox
  url: sandbox/thetadata-sandbox.yml
- type: Conventions
  url: conventions/thetadata-conventions.yml
- type: Idempotency
  url: conventions/thetadata-conventions.yml
- type: ChangeLog
  url: changelog/thetadata-changelog.yml
- type: Components
  url: components/thetadata-components.yml
- type: DataModel
  url: data-model/thetadata-data-model.yml
- type: RateLimits
  url: rate-limits/thetadata-rate-limits.yml
- type: Plans
  url: plans/thetadata-plans.yml
- type: AgentSkill
  url: skills/_index.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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ThetaData

APIs 7

Postman Collections 12

Open Collections 13

Pricing Plans 1

Rate Limits 1

Event Specifications 1

Security Posture 2

Get Started 4

Documentation 2

Agent Surfaces 3

Design & Contract 7

Build 5

Access & Security 2

Operate 6

Commercial 4

Company 3

Other 7

Source (apis.yml)

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