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 13 APIs on the APIs.io network, including Streaming WebSocket API, At-Time API, Calendar API, and 10 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 28 more developer resources.

🌐 Visit website 📡 Source on GitHub

63.1/100 strong ▬ flat Agent 64/100 agent native Full breakdown ↓
scored 2026-07-27 · rubric v0.5

AccessFreemiumFree trial⚡ Free to try

14 APIs 1 MCP Servers

FinancialMarket DataOptionsStocksIndicesReal-TimeHistorical DataTrading

Kin Score

Kin Score How this is scored →
scored 2026-07-27 · rubric v0.5

Composite quality — 63.1/100 · strong

Contract Quality 14.5 / 25

Developer Ergonomics 14.3 / 20

Commercial Clarity 15.3 / 20

Operational Transparency 10.6 / 13

Governance 0.0 / 12

Discoverability 10.0 / 10

Agent readiness — 64/100 · agent native

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 15

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 6 / 6

Agent Skills 5 / 5

Well-Known Catalog 4 / 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/thetadata: 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 14

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

MCP Servers 1

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

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 4

SDKs, sample code, and the tooling you integrate with

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

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.
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: '0.19'
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: MCPServer
    url: mcp/thetadata-mcp.yml
  - 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-at-time-api
  name: ThetaData At-Time API
  description: The At-Time API from ThetaData — 5 operation(s) for at-time.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - At-Time
  properties:
  - type: OpenAPI
    url: openapi/thetadata-at-time-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-at-time-api-overlay.yaml
- 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-flatfile-api
  name: ThetaData FlatFile API
  description: The FlatFile API from ThetaData — 6 operation(s) for flatfile.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - FlatFile
  properties:
  - type: OpenAPI
    url: openapi/thetadata-flatfile-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-flatfile-api-overlay.yaml
- aid: thetadata:thetadata-history-api
  name: ThetaData History API
  description: The History API from ThetaData — 26 operation(s) for history.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - History
  properties:
  - type: OpenAPI
    url: openapi/thetadata-history-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-history-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-list-api
  name: ThetaData List API
  description: The List API from ThetaData — 9 operation(s) for list.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - List
  properties:
  - type: OpenAPI
    url: openapi/thetadata-list-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-list-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-single-day-api
  name: ThetaData Single Day API
  description: The Single Day API from ThetaData — 2 operation(s) for single day.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Single Day
  properties:
  - type: OpenAPI
    url: openapi/thetadata-single-day-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-single-day-api-overlay.yaml
- aid: thetadata:thetadata-snapshot-api
  name: ThetaData Snapshot API
  description: The Snapshot API from ThetaData — 17 operation(s) for snapshot.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Snapshot
  properties:
  - type: OpenAPI
    url: openapi/thetadata-snapshot-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-snapshot-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
- aid: thetadata:thetadata-year-api
  name: ThetaData Year API
  description: The Year API from ThetaData — 1 operation(s) for year.
  humanURL: https://docs.thetadata.us/
  baseURL: http://127.0.0.1:25503/v3
  tags:
  - Year
  properties:
  - type: OpenAPI
    url: openapi/thetadata-year-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-year-api-overlay.yaml
common:
- 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

ThetaData

Kin Score

APIs 14

ThetaData Streaming WebSocket API

ThetaData MCP Server

ThetaData At-Time API

ThetaData Calendar API

ThetaData FlatFile API

ThetaData History API

ThetaData Index API

ThetaData Interest Rate API

ThetaData List API

ThetaData Option API

ThetaData Single Day API

ThetaData Snapshot API

ThetaData Stock API

ThetaData Year API

MCP Servers 1

thetadata-mcp.yml

Pricing Plans 1

Thetadata Plans

Rate Limits 1

Thetadata Rate Limits

Event Specifications 1

ThetaData Streaming WebSocket API (derived)

Security Posture 2

Thetadata Authentication

Thetadata Domain Security

Resources