---
title: "About CTC Finder and Our Data Sources"
description: "CTC Finder is an independent Clean Truck Check tester directory built from CARB's public tester list. How the data is collected, cleaned and refreshed."
url: "https://ctcfinder.com/about/"
updated: "2026-11-01"
publisher: "CTC Finder (independent directory, not affiliated with CARB)"
---

# About CTC Finder

## What CTC Finder is

CTC Finder is an independent directory that helps truck owners, fleets and owner-operators find a CARB-credentialed tester for California's Clean Truck Check (HD I/M) program. It is **not affiliated with, endorsed by or operated by the California Air Resources Board (CARB)** or any government agency. We do not register vehicles, collect CARB fees or issue compliance certificates; those happen only in CARB's CTC-VIS system.

## Where the data comes from

- **Testers:** CARB's public [Clean Truck Check tester list](https://cleantruckcheck.arb.ca.gov/Public/PublicTester/TesterList), last downloaded November 1, 2026. Listing on that list is optional, so some credentialed testers are missing. We list 2,867 testing businesses in California and 506 outside California.
- **Merging:** CARB lists each credentialed person separately. Entries with the same phone number and ZIP code, or the same business name and street address, are shown as one business with a tester count.
- **Cleaning:** advertising text in names (phone numbers, "book online at…") is removed. Website addresses found in names are kept as the business website.
- **Location:** ZIP code centers from the US Census Bureau (2024 ZCTA gazetteer) and ZIP-to-county relationships (2020). Distances are approximate.
- **Privacy:** we never publish testers' personal names or email addresses. When a listing looks like a home-based or mobile tester (a person's name or an apartment address), we hide the street address.
- **Prices and rules:** guide facts come from CARB's fact sheets, FAQ and regulations (13 CCR § 2195–2198). Price ranges come from testers' published prices. Each guide lists its sources.

## Refresh schedule

We refresh tester data from CARB every month and show a "last verified" date on every page. Featured listings are paid placements and are always labeled "Featured".

## Corrections and removal

Testers can correct or remove their listing at any time: [claim or update a listing](/for-testers/#claim) or email hello@ctcfinder.com.