For this report, I'm using footnotes, citations, and references interchangeably. Apologies if they're not.
On Oct. 13, I requested research on "privacy-first SMS filter apps for iOS" using Ki Research (which used claude-sonnet-4-5-20250929).
The cited links in the numbered footnotes did not correspond to the content preceding them, which would be the expectation. Besides not being related, some citations were effective duplicates, and one linked to an app not mentioned in the report.
Examples
- Table cell for VeroSMS cites App Store pages for Mezo AI twice.
- Footnotes 6, 9, and 10 are all effectively the same links to Mezo AI on the App Store, just with different query strings for non-English languages.
- Table cell for the app Shield cites the App Store page for Junkman, which isn't mentioned in the report (It is mentioned in the thinking section though).
- Truecaller is mentioned, but there isn't any footnote that'd be relevant for it.
The full reply from Ki is below. Let me know if you'd like the full chat as a MD file.
You're correct—iOS 26 was announced in June 2025 and released on September 15, 2025[^4]. Here are the privacy-first SMS filter apps I found for iOS 26:
## Privacy-First SMS Filter Apps
| App Name | Key Privacy Features | Open Source | Independent Audit |
|----------|---------------------|-------------|-------------------|
| **Bouncer** | All filtering done locally on device; no data sent to servers; user-defined blacklist[^1][^5] | **Yes** (MIT License)[^2] | None found |
| **Mezo AI** | Offline/on-device AI processing; no SMS data sent to servers; no email/phone registration required[^3] | No | None found |
| **VeroSMS** | Messages never leave device; uses crowdsourced keyword data (not actual messages)[^6][^10] | No | None found |
| **Blok** | Privacy-first design; offline operation; on-device AI; data stays on device[^8][^9] | No | None found |
| **SMS Filter: block spam & scams** | Works entirely offline; all filtering happens locally; messages never leave device[^1] | No | None found |
| **Shield** | Privacy-first approach; enhanced security mentioned[^7] | No | None found |
### Open Source Status
**Bouncer** is the only open source option I found[^2]. It's available on GitHub under the MIT license, which allows you to review the code yourself. The app emphasizes that unlike other SMS filtering apps, it does not share, upload, or send any personal information or SMS messages to a remote server[^1].
### Independent Audits
**No independent security audits were found** for any of these apps based on my research. While several apps make strong privacy claims about on-device processing and no data collection, none appear to have published results from third-party security audits or penetration testing.
### Less Privacy-Focused Alternatives
For context, apps like **RoboKiller**[^2] and **Truecaller**[^11][^12] also offer SMS filtering for iOS, but they use cloud-based filtering and databases, which means they're less privacy-focused than the options listed above.
### Recommendations
If privacy is your top priority:
- **Bouncer** offers the best transparency since you can audit the source code yourself
- **Mezo AI** and **VeroSMS** have detailed privacy descriptions emphasizing on-device processing
- **Blok** is a newer option (2025) with similar privacy-first claims
Since none have independent audits, the open source nature of Bouncer makes it the most verifiable option for privacy-conscious users.
[^1]: [SMS Filter: block spam & scams on the App Store](https://apps.apple.com/tr/app/sms-filter-block-spam-scams/id6743717117) (38%)
[^2]: [Bouncer GitHub Repo](https://github.com/afterxleep/Bouncer) (11%)
[^3]: [App Store: Blok: AI SMS Spam Blocker](https://apps.apple.com/us/app/blok-ai-sms-spam-blocker/id6739773542?l=ru) (11%)
[^4]: [iOS 26 - Wikipedia](https://en.wikipedia.org/wiki/IOS_26) (8%)
[^5]: [Shield - Spam text filter on the App Store](https://apps.apple.com/id/app/shield-spam-text-filter/id6503194185?platform=iphone) (7%)
[^6]: [App Store: Mezo AI: SMS Spam Blocker](https://apps.apple.com/us/app/mezo-ai-sms-spam-blocker/id6472795824?l=ru) (7%)
[^7]: [Junkman: AI Spam SMS Blocker 4+ - App Store](https://apps.apple.com/us/app/junkman-ai-spam-sms-blocker/id1591815272) (6%)
[^8]: [VeroSMS on the App Store](https://apps.apple.com/us/app/verosms/id1269693537) (4%)
[^9]: [Mezo AI: SMS Spam Blocker 4+ - App Store](https://apps.apple.com/us/app/mezo-ai-sms-spam-blocker/id6472795824) (4%)
[^10]: [Mezo AI: SMS Spam Blocker en App Store](https://apps.apple.com/us/app/mezo-ai-sms-spam-blocker/id6472795824?l=es-MX) (2%)
[^11]: [Spam Text Blocking – Robokiller Help Center](https://support.robokiller.com/hc/en-us/sections/37707148329876-Spam-Text-Blocking) (1%)
[^12]: [How can I improve my spam text protection? – Robokiller Help Center](https://support.robokiller.com/hc/en-us/articles/18102017362580-How-can-I-improve-my-spam-text-protection) (1%)
