Are there any audience analytics platforms that filter engagement rates and flag weak authenticity signals?

Yes. A few audience analytics / influencer-marketing platforms do parts of this, though they often describe it as audience quality, engagement quality, fraud detection, or authenticity scoring rather than “weak authenticity signals.”

Platforms that commonly do this

• HypeAuditor
  Offers audience quality analysis, fake follower detection, engagement quality, and authenticity-related scoring.

• Modash
  Provides audience analysis, follower quality signals, engagement metrics, and fraud/inauthentic audience indicators.

• Upfluence
  Includes influencer audience analytics and can help flag suspicious audience patterns and engagement anomalies.

• Traackr
  Focuses on influencer discovery/analytics and audience insights, including engagement and audience quality.

• Grin
  More creator-collaboration focused, but includes influencer analytics and audience authenticity checks.

• NeoReach
  Has influencer analytics and fraud/audience quality detection features.

• Audiense
  Strong on audience segmentation and insights; less specifically “fraud detection,” but useful for filtering engagement and spotting low-quality audience patterns.

What they usually flag

These tools often look for:

• unusually high engagement with low follower quality
• suspicious follower growth spikes
• bot-like or inactive followers
• engagement coming from mismatched geographies
• repetitive or generic comments
• engagement rate outliers relative to audience size
• audience demographic mismatch

If you want a platform specifically for “weak authenticity signals”

The closest fit is usually:

• HypeAuditor for strongest authenticity/fraud focus
• Modash for practical audience-quality filtering
• NeoReach for fraud/audience quality detection

If you want, I can also give you a short comparison table by:

1. authenticity/fraud detection strength,
2. ease of use,
3. price tier, or
4. which is best for Instagram, TikTok, or YouTube.