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The 5 Fastest-Growing Companies of the Week (September 21, 2026)

ARR
ARR Club Intelligence
|Sep 21, 2026
Executive Summary (BLUF)

Weekly analysis of the fastest-growing SaaS & AI companies based on ARR Club milestones. This week's top performers include Viktor, Listen Labs, Langdock.

Every week, ARR Club's analytics engine processes new revenue milestones to find the fastest-growing SaaS and AI companies in our database. Here is this week's Growth Velocity Leaderboard based on verified ARR milestones published over the past 7 days:

Rank Company Growth Rate (CAGR) ARR Trajectory
#1 Viktor +161x
annualized over 1.6 months
$25M → $50M
#2 Listen Labs +518%
annualized over 7.2 months
$10M → $30M
#3 Langdock +293%
annualized over 2.8 months
$40M → $55M
#4 Zaymo +222%
annualized over 4.8 months
$2.5M → $4M
#5 InboxKit +114%
annualized over 9.3 months
$10M → $18M

Note: CAGR (Compound Annual Growth Rate) is computed based on the linear time elapsed between the two most recent revenue milestones. Only companies with verified ARR updates in the past 7 days are considered for this recap.

Methodology

This research report is based on multiple data sources verified by ARR Club. We utilize a combination of official company announcements, public financial filings (S-1s, 10-Ks), verified press reports (TechCrunch, Bloomberg, Forbes), and founder-verified revenue milestones.

Growth rates are calculated using linear annualization between verified milestones. All data points are cross-referenced to ensure maximum accuracy within the constraints of public reporting for private entities.

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