WattTime

WattTime is a nonprofit organization that provides real-time, forecast, and historical data for electric grids around the world, enabling carbon-aware computing and clean energy procurement decisions. The WattTime API delivers marginal emissions data (CO2 MOER), health damage signals, average emissions rates, and renewable energy forecasts for 342 grid regions across 210 countries and territories. Developers and organizations use the API to schedule workloads during low-carbon windows, measure actual emissions reductions from clean energy procurement, and meet sustainability reporting requirements.

2 APIs 7 Features

EmissionsClimateCarbonEnergyElectricity GridSustainabilityClean Energy

APIs

WattTime API

The WattTime Data API v3 provides access to real-time, forecast, and historical marginal emissions data for electric grids worldwide. Key signals include CO2 MOER (Marginal Oper...

WattTime Python Client

Official Python SDK for the WattTime API providing simplified access to real-time, forecast, and historical emissions data.

Collections

WattTime API

OPEN

Pricing Plans

Watttime Plans Pricing

3 plans

PLANS

Rate Limits

Watttime Rate Limits

5 limits

RATE LIMITS

FinOps

Watttime Finops

FINOPS

Features

Real-Time Marginal Emissions

CO2 MOER signal providing real-time marginal carbon intensity for local grid regions, updated every 5 minutes via the forecast endpoint.

Emissions Forecasting

24-72 hour ahead emissions forecasts enabling applications to schedule energy-intensive workloads during low-carbon grid windows.

Historical Data Access

Historical MOER data available for up to 32 days via the data endpoint, and multi-year historical datasets downloadable as CSV files.

Health Damage Signal

Estimates the damage to human life and health caused by emissions from electricity generation based on time and location of consumption.

Global Grid Coverage

Coverage across 342 grid regions in 210 countries and territories, including North America, Europe, and global expansion with synthetic demand proxy models.

Grid Region Discovery

Identify the relevant balancing authority for any geographic coordinates and retrieve the list of accessible grid regions.

Model Versioning

Date-based model versioning (e.g., 2026-03-01) allowing unique versions per region and signal for reproducibility and comparison.

Use Cases

Carbon-Aware Computing

Technology companies and cloud providers schedule compute workloads, data transfers, and batch jobs to run during periods of low marginal carbon intensity.

Clean Energy Procurement

Organizations measure the actual emissions reductions from renewable energy procurement and power purchase agreements using marginal emissions data.

Sustainability Reporting

Enterprises report Scope 2 emissions more accurately using marginal emissions rates rather than average grid emission factors.

Smart Building Optimization

Building energy management systems shift heating, cooling, and EV charging to low-emission grid windows to reduce carbon footprint.

Grid Research and Analysis

Researchers, utilities, and policy makers analyze historical and forecast emissions data to study grid decarbonization trends.

Integrations

Green Software Foundation

WattTime provides the carbon intensity data underlying the Green Software Foundation's Software Carbon Intensity (SCI) specification.

Climate TRACE

WattTime contributes emissions data and modeling to the Climate TRACE global emissions inventory.

Impact Framework

Official Green Software Foundation Impact Framework plugin available for integrating WattTime data into software sustainability measurements.

Semantic Vocabularies

Watttime Context

13 classes · 25 properties

JSON-LD

API Governance Rules

WattTime API Rules

31 rules · 13 errors 17 warnings 1 info

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API Documentation

Documentation

📄

API Release Notes

WattTime GitHub Organization

WattTime Spectral Rules

SpectralRules

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WattTime Vocabulary

Vocabulary

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WattTime JSON-LD Context

JSONLD

Sources

opencollection: 1.0.0
info:
  name: WattTime API
  version: '3.0'
items:
- info:
    name: Authentication
    type: folder
  items:
  - info:
      name: WattTime Register New Account
      type: http
    http:
      method: POST
      url: https://api.watttime.org/v3/register
      body:
        type: json
        data: '{}'
    docs: Create a new WattTime API account. Registration requires a username, password, email, and organization. After registration,
      use the login endpoint to obtain an access token.
  - info:
      name: WattTime Login and Obtain Access Token
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/login
      auth:
        type: basic
        username: '{{username}}'
        password: '{{password}}'
    docs: Authenticate using HTTP Basic Auth (username and password) to obtain a JWT bearer token. The token expires after
      30 minutes and must be included as an Authorization Bearer header on all subsequent API calls. If a data call returns
      HTTP 401, re-authenticate to get a new token.
- info:
    name: Account
    type: folder
  items:
  - info:
      name: WattTime Get My Access Information
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/my-access
      params:
      - name: signal_type
        value: co2_moer
        type: query
        description: Filter results by signal type. Valid values include co2_moer, co2_aoer, health_damage.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Returns the list of grid regions and signal types accessible to the authenticated account, along with model metadata
      including available model versions by region and signal. Useful for determining which regions and signals are available
      under the current subscription plan.
- info:
    name: Grid Regions
    type: folder
  items:
  - info:
      name: WattTime Get Grid Region from Location
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/region-from-loc
      params:
      - name: latitude
        value: '37.7749'
        type: query
        description: Latitude of the location in decimal degrees.
      - name: longitude
        value: '-122.4194'
        type: query
        description: Longitude of the location in decimal degrees.
      - name: signal_type
        value: co2_moer
        type: query
        description: Signal type to check region availability for. Defaults to co2_moer.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Identify the electric grid balancing authority or region for a given set of geographic coordinates (latitude and
      longitude). Returns the region identifier used in subsequent data requests.
  - info:
      name: WattTime Get Grid Region Boundary Maps
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/maps
      params:
      - name: signal_type
        value: co2_moer
        type: query
        description: Filter maps by signal type availability.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Retrieve GeoJSON files showing the geographic boundaries of electric grid balancing authorities and grid regions
      accessible to the authenticated account. Useful for visualizing grid coverage areas on maps and verifying region boundaries.
- info:
    name: Emissions Data
    type: folder
  items:
  - info:
      name: WattTime Get Historical Emissions Data
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/data
      params:
      - name: region
        value: CAISO_NORTH
        type: query
        description: Grid region identifier (e.g., CAISO_NORTH). Obtain from /region-from-loc or /my-access.
      - name: signal_type
        value: co2_moer
        type: query
        description: 'The emissions signal type to retrieve. Valid values: co2_moer, co2_aoer, health_damage.'
      - name: start
        value: '2026-04-01T00:00:00Z'
        type: query
        description: Start of the time window in ISO 8601 format (UTC). Maximum window is 32 days.
      - name: end
        value: '2026-04-02T00:00:00Z'
        type: query
        description: End of the time window in ISO 8601 format (UTC).
      - name: model
        value: '2026-03-01'
        type: query
        description: Model version date to use (e.g., 2026-03-01). Defaults to the latest available model for the region.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Retrieve historical emissions data for a specified grid region and signal type within a time window. The maximum
      query window is 32 days. For longer historical datasets, use the /historical endpoint to download CSV files. Available
      to ANALYST and PRO subscribers; preview available for CAISO_NORTH.
  - info:
      name: WattTime Download Historical Emissions CSV
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/historical
      params:
      - name: region
        value: CAISO_NORTH
        type: query
        description: Grid region identifier (e.g., CAISO_NORTH).
      - name: signal_type
        value: co2_moer
        type: query
        description: The emissions signal type.
      - name: start
        value: '2023-01-01'
        type: query
        description: Start date for historical data download (YYYY-MM-DD).
      - name: end
        value: '2024-01-01'
        type: query
        description: End date for historical data download (YYYY-MM-DD).
      - name: model
        value: '2026-03-01'
        type: query
        description: Model version date.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Download multi-year historical emissions data as compressed CSV files. Returns a URL to download the CSV file for
      the specified grid region, signal type, and date range. Available to ANALYST and PRO subscribers.
- info:
    name: Forecasts
    type: folder
  items:
  - info:
      name: WattTime Get Emissions Forecast
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/forecast
      params:
      - name: region
        value: CAISO_NORTH
        type: query
        description: Grid region identifier (e.g., CAISO_NORTH).
      - name: signal_type
        value: co2_moer
        type: query
        description: The emissions signal type to forecast.
      - name: horizon_hours
        value: '24'
        type: query
        description: Number of hours ahead to forecast. Maximum varies by region. Default returns the full available forecast
          window.
      - name: model
        value: '2026-03-01'
        type: query
        description: Model version date to use. Defaults to the latest model.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Retrieve the current emissions forecast for a specified grid region and signal type. Real-time data is available
      within 5 minutes via this endpoint, covering a 24-72 hour forecast horizon. This is the primary endpoint for carbon-aware
      scheduling applications.
  - info:
      name: WattTime Get Historical Forecast Data
      type: http
    http:
      method: GET
      url: https://api.watttime.org/v3/forecast/historical
      params:
      - name: region
        value: CAISO_NORTH
        type: query
        description: Grid region identifier (e.g., CAISO_NORTH).
      - name: signal_type
        value: co2_moer
        type: query
        description: The emissions signal type.
      - name: start
        value: '2026-04-01T00:00:00Z'
        type: query
        description: Start of the historical forecast window (ISO 8601 UTC).
      - name: end
        value: '2026-04-02T00:00:00Z'
        type: query
        description: End of the historical forecast window (ISO 8601 UTC).
      - name: model
        value: '2026-03-01'
        type: query
        description: Model version date.
      auth:
        type: bearer
        token: '{{bearerToken}}'
    docs: Retrieve previously generated forecast data for a specific historical time window. Useful for back-testing carbon-aware
      scheduling algorithms and analyzing forecast accuracy over time.
bundled: true