SourcesThe data family
justicedata.dev
A free, keyless copy of the FBI's monthly reported crime counts by state, with a column that tells you how much of each state's population the reporting police agencies cover.
What it is
justicedata.dev republishes crime statistics from the FBI’s Uniform Crime Reporting (UCR) Program, taken from the FBI’s Crime Data Explorer. It serves them as plain JSON, CSV and Parquet files behind one API, with no key or signup. Like this site, it’s run by Eric Ness, so read this page as a description of a sibling, and check it the way you would any other source.
The site doesn’t produce any numbers itself. It names its source, license and an exact credit line.
What it measures
The site has one dataset, Crimes reported each month, by state (crime-monthly). It covers every state and the US, monthly since January 2018, in two series:
- Violent crime: murder and nonnegligent manslaughter, rape, robbery and aggravated assault.
- Property crime: burglary, larceny-theft and motor vehicle theft.
For each month and place you get the offenses police reported, the offenses cleared by arrest or “exceptional means,” rates per 100,000 people, the state’s population, and the population covered by the agencies that reported that month. The coverage_pct column is the share of the population those agencies cover.
These are reported figures, not estimates. The FBI’s annual reports fill in for agencies that didn’t report; this dataset doesn’t. That is why the coverage column matters so much: a state’s offense count drops when fewer agencies report, even if crime didn’t change. The rates are calculated per 100,000 people covered by reporting agencies, which helps, but only if the agencies that did report are typical of the state. For the US as a whole, the site gives rates and coverage but leaves the offense counts empty.
The site checks the FBI’s data every seven days and validates each update before publishing. Like its siblings, it gives every update a version ID with a fixed URL.
What it misses
Only crimes reported to police. The UCR Program counts offenses known to law enforcement. A crime nobody reports never appears. The Bureau of Justice Statistics runs a separate survey, the National Crime Victimization Survey, that asks people about crimes whether or not they reported them to police.
Not every agency reports. Most local agencies take part voluntarily, and each agency is responsible for the accuracy of its own numbers. For 2024, the FBI says reporting agencies covered 95.6 percent of the population served by agencies in the program. Coverage varies by state and by month.
The 2021 break. On January 1, 2021, the FBI stopped taking the old Summary Reporting System (SRS) and switched to the National Incident-Based Reporting System (NIBRS). Many agencies weren’t ready. The FBI says that despite more than 11,500 agencies sending NIBRS data for 2021, participation was too low to be nationally representative for trends. You can see this in the data: national coverage on justicedata.dev fell from about 97 percent in early 2020 to about 75 percent in January 2021, and in Florida it was under 50 percent for early 2021. For 2022 to 2024, the FBI accepted SRS data again from agencies that hadn’t switched. Treat any 2020-to-2021 comparison with care.
The two systems count differently. SRS used a hierarchy rule: when one incident included several crimes, only the most serious was counted. NIBRS records up to 10 offenses per incident. The FBI notes that agencies moving to NIBRS can appear to have more crime because more is recorded, not because more happened.
The latest months are incomplete. Agencies report late. On November 14, 2026, national coverage was about 85 percent for June 2026, about 52 percent for September and about 19 percent for October, and November had no data yet. Recent counts will rise as reports come in. Check coverage_pct before reading anything into the last few months.
The .dev layer has its own limits. It starts in 2018, stops at the state level (no cities, counties or individual agencies), and carries only the two summary categories, not individual offenses, victims, arrests or hate crimes. It is a copy. For anything high-stakes, go to the Crime Data Explorer itself and to the FBI’s published estimates.
How to access it
1Browse the catalog
Open justicedata.dev/datasets or ask the API:
curl -s "https://api.justicedata.dev/v1/catalog"
2Read the dataset’s metadata
https://api.justicedata.dev/v1/crime-monthly returns the version, coverage, source, license, credit line and download links.
3Get one series for one place
The pattern is /v1/{dataset}/{series}/{location}.csv (or .json). This call returns violent crime in California, one row per month:
curl -s "https://api.justicedata.dev/v1/crime-monthly/violent-crime/us-ca.csv"
Tested on November 14, 2026, it returned rows from 2018-01 onward, with columns date, offenses, clearances, offense_rate, clearance_rate, coverage_pct, population and covered_population. Use property-crime for the other series and usa for national rates.
4Download the whole dataset
https://api.justicedata.dev/v1/crime-monthly/download/crime-monthly.csv (or .parquet) gives every series and state in one file.
5Pin a version
Add @ and a version ID after the dataset ID, and the URL will always return the same data. /v1/crime-monthly/versions lists the current version and the monthly snapshots. The docs and the API reference cover caching, errors and every endpoint.
How to cite it
Cite the FBI and the exact version you used. Because recent months fill in as agencies report, the version ID is the only way a reader can see the same numbers you did.
The Sources page gives the credit line, and the docs say to cite the monthly snapshots, which are kept permanently. Other versions may be removed after 30 days.
A worked example for California’s violent crime series:
Federal Bureau of Investigation, Crime Data Explorer, https://cde.ucr.cjis.gov/ (summarized offenses, via the CDE API on api.data.gov). Accessed via justicedata.dev, dataset crime-monthly, version 2026-11-07.0251e3a173: https://api.justicedata.dev/v1/crime-monthly@2026-11-07.0251e3a173/violent-crime/us-ca.csv. Retrieved November 14, 2026.
In your text, give the coverage for the months you cite, and say these are reported crimes, not FBI estimates.
Sources & further reading
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