Short answer: no. Here's what to use instead.
No. As of 2026, EPA WebFIRE (the Factor Information REtrieval Data System) is web-only - you search through the EPA's browser interface, you cannot call it programmatically. The same is true of EPA's other emission factor programs: AP-42, CHIEF, and the GHG Emission Factors Hub. None expose public REST APIs. To access this data programmatically, download the EPA bulk source files and build your own search index.
The EPA's WebFIRE is a searchable web tool that returns emission factors filtered by Source Classification Code (SCC), pollutant, and control technology. It surfaces factors from AP-42 (the EPA's reference compilation) plus additional industrial source data. Used heavily for air quality permitting, Title V applications, and Scope 1 inventory work.
The interface accepts query parameters and returns formatted results with citations - but only via the browser. There is no documented JSON endpoint, no API key system, no rate-limited public REST surface in 2026.
The data behind WebFIRE is published as bulk downloads on epa.gov. If you need WebFIRE-equivalent data programmatically and can invest the engineering time, this is the path: download the source files, parse them, build an internal search index. You own the data layer end-to-end. The work is non-trivial because the data is structured around SCC codes with applicability conditions described in prose.
Climatiq includes a curated subset of AP-42 factors in their data layer. Not comprehensive coverage of WebFIRE, but it covers common combustion sources and integrates into their broader carbon accounting API. Enterprise pricing tier.
Most teams searching for "WebFIRE alternative" actually need electricity emission factors for Scope 2 reporting - for which WebFIRE is overkill anyway. emission-factors.com wraps EPA eGRID2023 Rev2 as a free API:
curl "https://emission-factors.com/api/lookup?zip=94105"Returns the eGRID subregion (CAMX), CO2e factor (0.1950 kg/kWh), generation mix, NOx, SO2, and carbon-free percentage. Free, no key, no signup. Also available as an MCP server for Claude and AI agents.
Often confused. AP-42 is the static reference document (Compilation of Air Pollutant Emission Factors). WebFIRE is the search UI that exposes AP-42 plus additional EPA data sources. Both lack APIs in 2026.
No public roadmap from EPA addresses this. EPA data modernization has prioritized real-time air quality (AirNow) and environmental justice screening (EJScreen). Emission factor APIs are not on the published roadmap as of 2026.
Don't. The underlying source data is published as bulk downloads on epa.gov. Scraping the UI is fragile and provides no advantage over the downloads.
Yes. WebFIRE, AP-42, and eGRID data are all in the public domain - free to download, redistribute, and use commercially.