Developer guides

List of companies using Greenhouse, Workday, Lever or Ashby: how to build one and why counts disagree

No ATS vendor publishes a list of its customers, so every "companies using Greenhouse" list is measured, and the published counts for the same vendor differ by a factor of ten because each method counts something different. Source: Arcadium Data, data as of 2026-10-25.

HR-tech sales teams, integration partners, recruiters choosing tools and investors all want a list of companies on a given applicant tracking system. A vendor's marketing page names a few dozen logos. The real list can only be built from outside: which companies have a public job board hosted by that vendor, and which of those boards are alive.

That is a measurement, and measurements disagree. For Ashby we have seen public counts of "500+", about 2,000, 2,800 and about 5,000 for the same period. The numbers are not wrong in the same way; they answer different questions. This guide shows how to build your own list and how to read someone else's.

How a customer list is built

Step 1: collect candidate boards

• Common Crawl. The monthly web crawl lists every captured URL. Querying its index for a hostname prefix (boards.greenhouse.io/*, jobs.lever.co/*, jobs.ashbyhq.com/*, *.myworkdayjobs.com) returns board tokens without sending a request to the vendor. Several crawls together give tens of thousands of candidates per vendor.
• Search engines and link graphs. The same hostnames appear in job aggregator and ATS-directory pages, but with copyright and terms questions; the crawl index is cleaner.
• Certificate transparency and DNS for vendors that give each customer a subdomain (Recruitee, Teamtailor, Personio, Workday tenants).

curl

# Common Crawl URL index: Greenhouse board pages in one crawl, first 5 results
curl -s "https://index.commoncrawl.org/CC-MAIN-2026-43-index?url=boards.greenhouse.io/*&output=json&limit=5"

Python

import json
import requests

def greenhouse_tokens(crawl: str = "CC-MAIN-2026-43", limit: int = 1000):
    r = requests.get(
        "https://index.commoncrawl.org/" + crawl + "-index",
        params={"url": "boards.greenhouse.io/*", "output": "json", "limit": limit},
        timeout=120,
    )
    r.raise_for_status()
    tokens = set()
    for line in r.text.splitlines():
        url = json.loads(line)["url"]
        parts = url.split("/")
        if len(parts) > 3 and parts[3] and parts[3] not in {"embed", "robots.txt"}:
            tokens.add(parts[3].lower())
    return sorted(tokens)

print(len(greenhouse_tokens()))

TypeScript

const url =
  'https://index.commoncrawl.org/CC-MAIN-2026-43-index?url=' + encodeURIComponent('jobs.lever.co/*') + '&output=json&limit=1000';
const text = await (await fetch(url)).text();
const tokens = new Set(
  text
    .split('\n')
    .filter(Boolean)
    .map((l) => new URL((JSON.parse(l) as { url: string }).url).pathname.split('/')[1]?.toLowerCase())
    .filter(Boolean),
);
console.log(tokens.size, 'candidate Lever boards in this slice');

Step 2: validate that a board is alive

A URL in an archive proves that a board once existed. Call the vendor's public endpoint (see the job board guide) and keep boards with at least one open job. In our own validation of about 34,000 candidates from eight crawls, 61% of Common Crawl candidates still had an open job; discovery from Common Crawl was roughly fifty times cheaper than probing domain guesses.

Step 3: attach the board to a company

The token is not the company. Map it to a domain from evidence in the board itself (links in job descriptions, the hosted board's own website field, the apply links' custom domain), and keep the evidence and a confidence. A name-only match is how "nuro" the Greenhouse board ends up under the wrong country.

Step 4: audit a sample before you trust the list

Whether you built a list or bought one, test it. Draw 100 rows at random and check three things by hand or by script: the board still has open jobs (liveness), the company on the row is the company that owns the board (attribution), and the vendor named is the one that serves the apply link (identification). Report the share that passes each check; a list that is 95% alive but 70% correctly attributed is a list of boards, not of companies. Repeat the audit when the source changes, because new discovery passes bring in different kinds of mistakes. Staffing agencies and job boards that list other employers' jobs belong in a separate column, not in a customer count.

Why published counts disagree

Why published counts disagree

• Alive or ever seen. Counting every board ever captured gives a large number; counting boards with open jobs today gives a smaller one.
• Boards or companies. One company can have several boards; one board can serve several brands.
• Sample or census. A crawl-based share is among the employers a crawl observed, which over-represents tech companies and English-language sites.
• Window. "Active in the last 90 days" and "active in the last year" differ by a lot for an ATS that people leave and join.
• Vendor coverage. Some vendors (Lever, in public archives) are poorly captured, which pushes their measured share down.

When you buy or quote a list, ask for four things: the definition of "using", the date, the sample, and how a board is tied to a company.

The fast route: market share, vendor pages and keyed lists

Arcadium Data publishes the measurement and its definition. Our boards come from Common Crawl discovery plus domain probing, validated against the vendor endpoints, and every board is tied to a company domain with evidence and a confidence.

Share and movement per vendor since February 2023: GET /v1/ats/market returns monthly share, the number of employers observed, wins (new employers), losses and dated switches in and out. The anonymous tier answers one vendor at a time with at most five rows:

Calls on this page work without a key from one IP (10 requests a minute, 100 a day, short answers, point lookups). A free key lifts the limits: sign up. Routes, parameters and fields: OpenAPI.

curl

curl -s "https://api.arcadiumdata.io/v1/ats/market?ats=greenhouse"

Response (abridged)

{
  "series": "core4",
  "country": "ALL",
  "sizeBand": "all",
  "note": "Share among the employers we observe in the Common Crawl public web archive (5 ATS host zones), not the whole market ...",
  "data": [{
    "month": "2023-02-01",
    "crawlId": "CC-MAIN-2023-06",
    "ats": "greenhouse",
    "share": 0.46380026,
    "employers": 1946,
    "wins": 0,
    "losses": 0,
    "switchesIn": 0,
    "switchesOut": 0
  }]
}

Read the note field: it states what the share is a share of, which crawls are included and where Lever drops out of the archive. With a key, country, sizeBand, from and to cut the series; live adds today's share among the ten ATS we crawl directly.

The lists themselves. The site publishes them as pages: /ats/ has one page per vendor with counts by country and department and the top companies, and the companies index lists every company by vendor, A to Z. Per-company lookups use GET /v1/companies/{domain} (see the ATS detection guide). Searching jobs by system needs a key:

curl

curl -s "https://api.arcadiumdata.io/v1/jobs?ats=workday&country=GB&limit=50" \
  -H "Authorization: Bearer $ARCADIUM_API_KEY"

Python

import requests

r = requests.get("https://api.arcadiumdata.io/v1/ats/market?ats=ashby", timeout=30)
r.raise_for_status()
body = r.json()
print(body["note"][:120])
for row in body["data"]:
    print(row["month"], row["ats"], round(row["share"], 3), row["employers"])

TypeScript

const res = await fetch('https://api.arcadiumdata.io/v1/ats/switches?domain=stripe.com');
const body = (await res.json()) as { count: number; note: string };
console.log(body.count, body.note);

Bulk lists for a licence (company, ATS, board URL, country, open jobs, last seen) are described on the data licence page, with samples. Our counts are a floor: companies we cannot tie to a domain are left out of switches and lists.

Comparison

Related

• ATS vendors and their companies
• ATS market share report
• Which ATS does a company use
• Job board APIs
• Workday career site JSON
• Data licence

Sources

• Common Crawl
• Common Crawl URL index server
• Greenhouse Job Board API
• Ashby public job posting API

Last updated 2026-10-25. This guide is ours and independent of the organisations it describes. Found a mistake? Tell us and we correct it.

Cite as: Arcadium Data, "List of companies using Greenhouse, Workday, Lever or Ashby: how to build one and why counts disagree", https://arcadiumdata.io/guides/companies-using-an-ats-greenhouse-workday-lists/, data as of 2026-10-25.