Perplexity Citation Change Log: 490 of the Top 500 Domains, Recorded Six Sources Deep
A dated record of what Perplexity cites and what changes. Entry one: Perplexity reaches 490 of the 500 most-cited domains, the widest head overlap of six engines, while AuthorityTech's own daily panel was recording only 6 of its ~20.8 sources per answer.
Perplexity Citation Change Log: 490 of the Top 500 Domains, Recorded Six Sources Deep
A dated record of what Perplexity cites and what changes, read from the Machine Relations Index and AuthorityTech's own daily panel. Entry one: Perplexity reaches 490 of the 500 most-cited domains in AI answers, the widest head overlap of six engines, and cites the leading source in all 93 published segments. The panel that tracks it day to day was recording a mean of 6 sources per answer against the roughly 20.8 the engine actually returns — disclosed here before any churn number built on it.
- Published: 2026-09-22
- Author: Paralax Editorial
- Canonical: https://paralax.ai/blog/perplexity-citation-change-log-2026
- Tags: ai-search, citations, measurement
Perplexity cites 9,986 of the 22,828 domains observed in AI answers — more distinct domains than any other engine measures against. That is the wide version of the story. The narrow version, the one that matters to a publisher deciding whether to chase this engine, is where those citations land: Perplexity reaches 490 of the 500 most-cited domains in the market, 244 of the top 250, and cites the single most-cited source in every one of the 93 published question segments. No other engine clears all three.
This log is a dated record of what Perplexity cites and what changes. Every entry states the measurement, the release or window it came from, the primary source, and what a publisher can check. Entries are appended; nothing is rewritten. Entry one draws on the Machine Relations Index, which observes six engines — Perplexity, ChatGPT, Claude, Gemini, Google AI Mode and Google AI Overviews — against a fixed basket of buying and research questions and publishes a machine-readable release daily. Entry one also covers a methodological finding about AuthorityTech's own daily panel that has to be on the record before this log uses that panel for anything: the panel's citation log keeps only the first six sources per answer, and it caught Perplexity worse than any other engine it tracks.
Entry 1 — September 22, 2026: the baseline
Release mri_score_v2.0, contract machine_relations_index_public_view_v2.0, generated September 22, 2026. Window May 10 to September 22, 129 days, 16,307 observed answer runs, 34,720 cited-domain observations, 22,828 cited domains. A subject category paired with a question type forms a stratum, and a stratum publishes a rate only after clearing an evidence floor of 10 observed runs across 7 distinct dates; 93 of the 151 measurable strata are published today.
The Index records, for each domain, which engines cited it at least once in the window. It does not publish a per-engine citation rate, so everything below is presence and counts, not per-engine rates — the same boundary this log's companion ChatGPT page runs under.
The widest head overlap of six engines
| Engine | Top 25 | Top 100 | Top 250 | Top 500 |
|---|---|---|---|---|
| Perplexity | 25 | 96 | 244 | 490 |
| Claude | 23 | 94 | 237 | 463 |
| Gemini | 23 | 89 | 227 | 452 |
| Google AI Mode | 24 | 91 | 227 | 444 |
| Google AI Overviews | 24 | 89 | 203 | 378 |
| ChatGPT | 22 | 88 | 203 | 361 |
Perplexity misses 10 of the top 500 most-cited domains in the market. Every other engine misses at least 37; ChatGPT, the narrowest, misses 139. This is the head-overlap comparison this log's ChatGPT entry now leads on, for the reason recorded in that page's September 22 correction: an unconditioned exclusive-domain share is mostly tail composition — sources cited once — and does not describe where an engine's evidence actually sits. Head overlap does, because it is ranked by citation frequency, not counted flat.
It also cites the leading source in every segment
For each of the 93 published strata, take the domain with the highest citation rate in that stratum — the source the engines cite most when buyers ask that category's question — then ask which engines cite that domain anywhere in the window.
| Engine | Cites the leading source, of 93 segments |
|---|---|
| Perplexity | 93 |
| Gemini | 86 |
| Google AI Mode | 81 |
| Google AI Overviews | 79 |
| Claude | 72 |
| ChatGPT | 66 |
Perplexity has not missed a single segment leader across the measured window. Combined with the head-overlap table, the two published facts about Perplexity's composition point the same direction: whatever else it does, this engine reliably reaches the source the market already concentrates on.
Domain count and the exclusive-share caveat, stated up front
Perplexity cites 9,986 domains, the most of any engine, ahead of Google AI Mode's 7,441 and Gemini's 7,118. Of those, 4,560 — 45.7% — are cited by no other engine in the window, the highest raw share of the six. Read that number the way the ChatGPT page's September 22 correction requires it to be read, not the way it is usually reported: at an evidence floor of 10 citations, Perplexity's exclusive pool falls from 4,560 domains to 18. The other 4,542 are sources cited once or a handful of times, which is tail composition, not a claim about where Perplexity's evidence concentrates. This page states the floor-adjusted number in the same entry it reports the raw one, rather than publishing the raw number first and correcting it four days later.
Community platforms: second-widest, one below Google AI Mode
Twenty-seven classified domains in the Index are community and social platforms — a small set where engines diverge most.
| Engine | Community platforms cited (of 27) |
|---|---|
| Google AI Mode | 20 |
| Perplexity | 18 |
| Gemini | 15 |
| Claude | 10 |
| Google AI Overviews | 10 |
| ChatGPT | 8 |
Of Perplexity's 1,618 classified citations (domains carrying a source-role tag; the other 8,368 domains it cites are uncategorised, so this is a share of the classified set, not of everything), 32.9% are editorial publications and 1.1% are community platforms. Perplexity is closer to Google AI Mode's community reach than to ChatGPT's.
The ten domains in the top 500 it does not cite
Perplexity is absent from 10 of the top 500 most-cited domains. Two are worth a robots.txt check because every other engine in the panel cites them.
| Rank | Domain | Class | Cited by | robots.txt, read 2026-09-22 |
|---|---|---|---|---|
| 166 | quora.com | Community | 4 of the other 5 engines | User-agent: PerplexityBot / Disallow: / — Perplexity named and blocked |
| 90 | researchgate.net | Academic/government | All other 5 engines | User-agent: * / Allow: / — no block on any agent |
Quora names PerplexityBot specifically and blocks it; that is a clean case of stated policy matching observed absence. ResearchGate blocks nothing — its robots.txt allows every user agent, including Perplexity's — and is absent from every Perplexity run in the window anyway. Perplexity's own crawler documentation distinguishes PerplexityBot, used to surface results in Perplexity's own search product, from Perplexity-User, triggered by a live user request; a publisher can permit one and block the other. Neither distinction explains ResearchGate. The remaining eight absent domains — itpro.com, tracxn.com, 6sense.com, pymnts.com, americanbar.org, pitchbook.com, infosecurity-magazine.com, prezly.com — carry no comparable contradiction and are not itemised here; this log will if any of them becomes load-bearing to a later entry.
What the daily panel was actually recording
AuthorityTech runs its own tracked panel alongside the Index: 35 fixed queries, five retrieval surfaces, once a day, the same instrument behind this log's ChatGPT entry two and the site's 89-day per-engine churn measurement. That page's September 22 correction found the daily log stores only the first six sources returned by each engine, and the cap does not bite every engine equally. It bites Perplexity hardest of all five.
Measured against the stored per-run answer artifacts, which preserve each provider's complete returned source list — available from September 1, 2026 onward, not for the full panel history — Perplexity returns a mean of 20.8 source URLs resolving to 15.3 distinct domains per answer. The daily log recorded a maximum of six. Perplexity's answers exceeded six sources on 350 of 350 runs in that window: every single one was truncated, against 91% of Gemini's runs, 16% of Claude's, 12% of ChatGPT's, and none of Google AI Mode's. Perplexity is the deepest answer of the five surfaces this panel tracks and the one the six-source cap distorted worst.
The practical consequence, recomputed rather than assumed small: day-over-day domain churn on Perplexity's complete source lists for the September 1–22 window (577 day pairs) is 20.0%, against 21.8% on the panel's six-source cap — an overstatement of 1.9 percentage points, in the direction the truncation predicts, with the cross-engine ranking unchanged. That correction and its full recomputation table live on the churn page linked above; this log will not restate the panel's older 89-day retention, drop-out, and core-domain figures as if they described the complete list, because the complete-list artifacts do not reach back past September 1 and the churn page says so explicitly. Any figure in this log drawn from the panel is labelled by which list produced it.
How to read this log
Each future entry compares a release or a panel window against the one before it and reports what moved. Four numbers are the ones to watch:
- Head overlap. 244 of the top 250, 490 of the top 500.
- Segment leaders cited. 93 of 93.
- Exclusive pool at an evidence floor. 18 domains cited only by Perplexity and cited at least ten times, on the September 22 release. The unconditioned 45.7% share is tail composition and is not tracked as a finding.
- Panel-recorded source depth. 15.3 distinct domains per answer on the complete list, against a six-item cap in the daily log; watch for the cap narrowing as the answer-evidence store's history lengthens past September 1.
A change in any of them is an entry. A release with none is recorded as no change.
What a publisher should take from entry one
Reaching the head of the index is not automatic just because an engine cites a lot of domains. ChatGPT cites 4,877 domains, well below Perplexity's 9,986, and still trails Perplexity by 129 domains in the top 500 (361 against 490). Perplexity's combination — widest raw domain count, widest head overlap, and a perfect segment-leader record — means presence in Perplexity is close to a proxy for presence in the market's actual citation head. Among the top 250 most-cited domains, only one, researchgate.net, is absent from Perplexity despite carrying no stated crawler block; that is the case worth watching, not the nine other, lower-ranked absences.
The second finding cuts the other way, against measurement, not against the engine. A dashboard, a competitor tracker, or an internal panel that caps a citation array anywhere below roughly 20 entries per answer will report a fraction of what Perplexity actually cites, understating both its reach and its churn. AuthorityTech's own panel did this for every day of its history through September 1, on 100% of Perplexity's runs, and only caught it by checking the complete artifact against the six-item log. A publisher relying on any vendor's Perplexity citation count should ask what the cap is before trusting the number.
Watch list for entry 2
- Whether Perplexity's head-overlap or segment-leader numbers move at the next Index release — the release updates daily, so entry 2 will report on genuine movement, not a fixed weekly cadence.
- Whether quora.com's
PerplexityBotblock lifts, or whether researchgate.net's continued absence despite an openrobots.txtdevelops an explanation. - Whether the complete per-run artifact history extends further back than September 1, letting the panel restate churn over a longer window than 22 days.
- Whether any additional top-500 domain drops out of or into Perplexity's cited set.
Frequently asked questions
Does citing more domains than any other engine mean Perplexity is a worse filter? Not on this measurement. Domain count and head concentration are not in tension here: Perplexity cites the most domains overall and still reaches the deepest into the head of the index. A wide base and a covered head are not mutually exclusive, and Perplexity is the one engine in this panel with both.
Why does the exclusive-share number in this entry not match a simpler "45.7% exclusive" headline? Because that headline was published and then withdrawn on this log's ChatGPT entry four days ago, for the reason given there: an unconditioned exclusive count is weighted almost entirely by domains cited once. This entry states the floor-adjusted number, 18 domains, in the same breath as the raw one, instead of publishing the misleading version first.
Is the six-source cap a Perplexity problem or a measurement problem? A measurement problem, and specifically AuthorityTech's own daily panel's problem, not the Machine Relations Index's — the Index used for entry one's composition figures is not affected by this cap. It is disclosed here, before this log uses the daily panel for anything, so that no churn or stability number in a future entry needs a correction after the fact.