Free JSON · no key · open CORS

Monday Diesel Data API

Every number published on Monday Diesel (mondaydiesel.com) as free JSON: the DOE number, regions, spot, crude oil, cost per mile and price history. No key, no sign-up, callable from any website or script. The files are rebuilt every time the site rebuilds with new data, so they always match the pages.

Base URL
https://mondaydiesel.com/api/v1
Auth
None
Format
JSON, UTF-8, GET only
CORS
Access-Control-Allow-Origin: *
Series
14 · 9 key statistics
Data as of
Nov 9, 2026

Quick start

The newest reading of every series, from a terminal:

curl https://mondaydiesel.com/api/v1/latest.json

Or in JavaScript, from any page:

const res = await fetch("https://mondaydiesel.com/api/v1/latest.json");
const { data_as_of, data } = await res.json();
for (const row of data) console.log(row.title, row.headline, row.data_through);

Endpoints

GET /api/v1/index.json

API index. What this API is, its license and attribution, the sections it covers, and every endpoint.

Example: https://mondaydiesel.com/api/v1/index.json

Sample response
{
  "api": "Monday Diesel Data API",
  "version": "v1",
  "docs": "https://mondaydiesel.com/api",
  "data_as_of": "2026-11-09",
  "data_as_of_label": "Nov 9, 2026",
  "data_pulled_at": "2026-11-11T00:15:05.839Z",
  "generated_at": "2026-11-11T18:51:15.096Z",
  "attribution": "Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.",
  "name": "Monday Diesel Data API",
  "description": "Free JSON for every number published on Monday Diesel (mondaydiesel.com): the DOE number, regions, spot, crude oil, cost per mile, price history. The Monday diesel number for people who get paid by the mile.",
  "publisher": {
    "name": "Monday Diesel",
    "url": "https://mondaydiesel.com"
  },
  "auth": "none",
  "cors": "*",
  "format": "application/json; charset=utf-8",
  "license": "Free to use and republish with attribution; no key or sign-up. The underlying figures are public records from the agencies named in each series' provenance; Monday Diesel collects, checks and publishes them.",
  "update_policy": "Static files rebuilt every time the site rebuilds with new data. data_as_of in each response is the newest observation it holds; data_pulled_at is when the site last pulled its sources.",
  "counts": {
    "series": 14,
    "stats": 9
  },
  "sections": [
    {
      "key": "number",
      "label": "The DOE number",
      "series": 1,
      "example": "https://mondaydiesel.com/api/v1/series/number/doe-diesel-price.json"
    },
    {
      "key": "region",
      "label": "Regions",
      "series": 9,
      "example": "https://mondaydiesel.com/api/v1/series/region/california.json"
    },
    {
      "key": "spot",
      "label": "Spot",
      "series": 1,
      "example": "https://mondaydiesel.com/api/v1/series/spot/gulf-coast.json"
    },
    {
      "key": "crude",
      "label": "Crude oil",
      "series": 1,
      "example": "https://mondaydiesel.com/api/v1/series/crude/diesel-vs-crude.json"
    },
    {
      "key": "costpermile",
      "label": "Cost per mile",
      "series": 1,
      "example": "https://mondaydiesel.com/api/v1/series/costpermile/diesel-cost-per-mile.json"
    },
    {
      "key": "diesel-price-history",
      "label": "Price history",
      "series": 1,
      "example": "https://mondaydiesel.com/api/v1/series/diesel-price-history/chart.json"
    }
  ],
  "endpoints": [
    {
      "method": "GET",
      "path": "/api/v1/index.json",
      "url": "https://mondaydiesel.com/api/v1/index.json",
      "description": "What this API is, its license and attribution, the sections it covers, and every endpoint."
    },
    {
      "method": "GET",
      "path": "/api/v1/latest.json",
      "url": "https://mondaydiesel.com/api/v1/latest.json",
      "description": "The newest reading of every data page on Monday Diesel (14 series): the headline value as the site shows it, the newest point of each charted line with its date, whether it is current, and links to its page and full history."
    },
    {
      "method": "GET",
      "path": "/api/v1/stats.json",
      "url": "https://mondaydiesel.com/api/v1/stats.json",
      "description": "The 9 headline numbers on the mondaydiesel.com/stats page, each as a quotable sentence with its data date and a ready-made citation."
    },
    {
      "method": "GET",
      "path": "/api/v1/series/{section}/{slug}.json",
      "url": "https://mondaydiesel.com/api/v1/series/number/doe-diesel-price.json",
      "description": "Everything behind one data page: every charted point (date + value), the historical band where the page draws one, the page's tables exactly as shown, its source and citation. Find each series_url in latest.json."
    },
    {
      "method": "GET",
      "path": "/api/v1/openapi.json",
      "url": "https://mondaydiesel.com/api/v1/openapi.json",
      "description": "A machine-readable OpenAPI 3.1 description of these endpoints."
    }
  ]
}

GET /api/v1/latest.json

Latest readings. The newest reading of every data page on Monday Diesel (14 series): the headline value as the site shows it, the newest point of each charted line with its date, whether it is current, and links to its page and full history.

Example: https://mondaydiesel.com/api/v1/latest.json

Sample response
{
  "api": "Monday Diesel Data API",
  "version": "v1",
  "docs": "https://mondaydiesel.com/api",
  "data_as_of": "2026-11-09",
  "data_as_of_label": "Nov 9, 2026",
  "data_pulled_at": "2026-11-11T00:15:05.839Z",
  "generated_at": "2026-11-11T18:51:15.096Z",
  "attribution": "Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.",
  "count": 14,
  "data": [
    {
      "id": "number/doe-diesel-price",
      "section": "number",
      "section_label": "The DOE number",
      "title": "This week's DOE on-highway diesel price",
      "headline": "$6.127/gal",
      "unit": "$/gal",
      "data_through": "2026-11-09",
      "frequency": "Weekly",
      "status": "current",
      "values": [
        {
          "series": "US average",
          "date": "2026-11-09",
          "value": 6.127
        }
      ],
      "source": "EIA Weekly Retail On-Highway Diesel Price survey",
      "page_url": "https://mondaydiesel.com/number/doe-diesel-price",
      "series_url": "https://mondaydiesel.com/api/v1/series/number/doe-diesel-price.json"
    },
    {
      "id": "region/california",
      "section": "region",
      "section_label": "Regions",
      "title": "California diesel price",
      "headline": "$7.897/gal",
      "unit": "$/gal",
      "data_through": "2026-11-09",
      "frequency": "Weekly",
      "status": "current",
      "values": [
        {
          "series": "California",
          "date": "2026-11-09",
          "value": 7.897
        },
        {
          "series": "US average",
          "date": "2026-11-09",
          "value": 6.127
        }
      ],
      "source": "EIA Weekly Retail On-Highway Diesel Price survey",
      "page_url": "https://mondaydiesel.com/region/california",
      "series_url": "https://mondaydiesel.com/api/v1/series/region/california.json"
    }
  ]
}

Trimmed to 2 of 14 entries.

GET /api/v1/stats.json

Key statistics. The 9 headline numbers on the mondaydiesel.com/stats page, each as a quotable sentence with its data date and a ready-made citation.

Example: https://mondaydiesel.com/api/v1/stats.json

Sample response
{
  "api": "Monday Diesel Data API",
  "version": "v1",
  "docs": "https://mondaydiesel.com/api",
  "data_as_of": "2026-11-09",
  "data_as_of_label": "Nov 9, 2026",
  "data_pulled_at": "2026-11-11T00:15:05.839Z",
  "generated_at": "2026-11-11T18:51:15.096Z",
  "attribution": "Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.",
  "stats_page": "https://mondaydiesel.com/stats",
  "count": 9,
  "stats": [
    {
      "id": "doe-number",
      "label": "The DOE number",
      "sentence": "US on-highway diesel averaged $6.127/gal in EIA's latest Monday release — the index most fuel surcharge schedules peg to.",
      "data_date": "2026-11-09",
      "citation": "US on-highway diesel averaged $6.127/gal for the week of Nov 9, 2026, per EIA's weekly release (the DOE Monday index). Monday Diesel. https://mondaydiesel.com/number/doe-diesel-price",
      "stats_url": "https://mondaydiesel.com/stats#doe-number",
      "page_url": "https://mondaydiesel.com/number/doe-diesel-price",
      "series_url": "https://mondaydiesel.com/api/v1/series/number/doe-diesel-price.json",
      "provenance": "EIA Weekly Retail On-Highway Diesel Price survey · US average on-highway retail diesel, No. 2 · On-highway retail pump, taxed · United States · through Nov 9, 2026"
    },
    {
      "id": "doe-weekly-move",
      "label": "Weekly move",
      "sentence": "The DOE diesel number fell 16.5 cents a gallon in the week of Nov 9, 2026.",
      "data_date": "2026-11-09",
      "citation": "The DOE diesel number fell 16.5 cents a gallon in the week of Nov 9, 2026. Monday Diesel. https://mondaydiesel.com/stats#doe-weekly-move",
      "stats_url": "https://mondaydiesel.com/stats#doe-weekly-move",
      "page_url": null,
      "series_url": null,
      "provenance": null
    }
  ]
}

Trimmed to 2 of 9 statistics.

GET /api/v1/series/{section}/{slug}.json

One series, full history. Everything behind one data page: every charted point (date + value), the historical band where the page draws one, the page's tables exactly as shown, its source and citation. Find each series_url in latest.json.

Example: https://mondaydiesel.com/api/v1/series/number/doe-diesel-price.json

Sample response
{
  "api": "Monday Diesel Data API",
  "version": "v1",
  "docs": "https://mondaydiesel.com/api",
  "data_as_of": "2026-11-09",
  "data_as_of_label": "Nov 9, 2026",
  "data_pulled_at": "2026-11-11T00:15:05.839Z",
  "generated_at": "2026-11-11T18:51:15.096Z",
  "attribution": "Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.",
  "id": "number/doe-diesel-price",
  "section": "number",
  "section_label": "The DOE number",
  "title": "This week's DOE on-highway diesel price",
  "subtitle": "This week's DOE diesel price is $6.127 a gallon, EIA's US on-highway average for the week of Nov 9, 2026, down 16.5 cents from the week before. EIA prices it as of Monday and posts it Tuesday; most fuel surcharge schedules peg to it.",
  "description": "Department of Energy (DOE) diesel price: $6.127/gal, EIA's US on-highway average for the week of Nov 9, 2026, down 16.5 cents. The fuel surcharge benchmark.",
  "page_url": "https://mondaydiesel.com/number/doe-diesel-price",
  "headline": "$6.127/gal",
  "unit": "$/gal",
  "data_through": "2026-11-09",
  "frequency": "Weekly",
  "status": "current",
  "source": "EIA Weekly Retail On-Highway Diesel Price survey",
  "provenance": {
    "source": "EIA Weekly Retail On-Highway Diesel Price survey",
    "series": "US average on-highway retail diesel, No. 2",
    "basis": "On-highway retail pump, taxed",
    "geography": "United States",
    "unit": "$/gal",
    "period": "Weekly survey, priced as of Monday",
    "lastObservation": "Nov 9, 2026",
    "frequency": "Weekly"
  },
  "citation": "US on-highway diesel averaged $6.127/gal for the week of Nov 9, 2026, per EIA's weekly release (the DOE Monday index). Monday Diesel. https://mondaydiesel.com/number/doe-diesel-price",
  "series": [
    {
      "label": "US average",
      "unit": "$/gal",
      "points": [
        {
          "date": "2026-10-26",
          "value": 6.352
        },
        {
          "date": "2026-11-02",
          "value": 6.292
        },
        {
          "date": "2026-11-09",
          "value": 6.127
        }
      ]
    }
  ],
  "tables": [
    {
      "caption": null,
      "columns": [
        "Period",
        "Current",
        "Prior",
        "Change"
      ],
      "rows": [
        [
          "Week over week",
          "$6.127/gal",
          "$6.292/gal",
          "-2.6%"
        ],
        [
          "vs 4 weeks ago",
          "$6.127/gal",
          "$6.179/gal",
          "-0.8%"
        ],
        [
          "Year over year",
          "$6.127/gal",
          "$3.837/gal",
          "+59.7%"
        ]
      ]
    }
  ]
}

Trimmed: the live response carries all 279 points, the full table.

GET /api/v1/openapi.json

OpenAPI description. A machine-readable OpenAPI 3.1 description of these endpoints.

Example: https://mondaydiesel.com/api/v1/openapi.json

Sample response
{
  "openapi": "3.1.0",
  "info": {
    "title": "Monday Diesel Data API",
    "version": "1.0.0",
    "description": "Free JSON for every number published on Monday Diesel (mondaydiesel.com): the DOE number, regions, spot, crude oil, cost per mile, price history. The Monday diesel number for people who get paid by the mile. No key needed. Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.",
    "license": {
      "name": "Free to use with attribution",
      "url": "https://mondaydiesel.com/api"
    }
  },
  "servers": [
    {
      "url": "https://mondaydiesel.com/api/v1"
    }
  ],
  "externalDocs": {
    "description": "Docs",
    "url": "https://mondaydiesel.com/api"
  },
  "paths": {
    "/index.json": {
      "get": {
        "operationId": "getIndex",
  ...

First lines only.

What's in it

One series file per data page on the site, at https://mondaydiesel.com/api/v1/series/{section}/{slug}.json. Every valid pair is listed in latest.json (its id and series_url fields).

SectionSeriesExample
The DOE numberEIA's Monday-priced on-highway diesel number, the benchmark most fuel surcharges peg to. 1 This week's DOE on-highway diesel price
RegionsOn-highway diesel by PADD, East Coast subregion and California, week over week. 9 California diesel price
SpotDaily ULSD spot at the Gulf Coast and New York Harbor, the wholesale layer under the pump, with the pump price over spot. 1 Diesel spot prices: Gulf Coast and New York Harbor
Crude oilThe pump price against WTI and Brent crude, the upstream cost behind roughly half of it. 1 Diesel price vs crude oil
Cost per mileThe DOE number translated to fuel cost per mile at a stated 6.5 mpg reference. 1 Diesel fuel cost per mile
Price historyEvery weekly DOE diesel price since 1994, by year and by region, with records and a CSV. 1 Diesel price history chart, 1994 to 2026

Fields every response carries

In latest.json and each series file, headline is the value exactly as the site shows it (with its unit), values / series carry the raw numbers with their dates, and status is current or not_current. A series that is out of season or not recently quoted says so, with last_quoted, rather than passing an old reading off as today's. See an example series.

Use, credit and limits

Free to use and republish with attribution; no key or sign-up. The underlying figures are public records from the agencies named in each series' provenance; Monday Diesel collects, checks and publishes them.

Attribution: Credit Monday Diesel (mondaydiesel.com) with a visible link to the page the figure came from; every record carries its page_url.

No rate limit is set and there is nothing to sign up for: the files are static and served from Cloudflare's network. Please cache responses rather than polling; they change only when the site rebuilds. Fields are only ever added within v1, never renamed or removed. Questions or a series you need: contact us. How each number is collected: methodology.