SynthGuard vs StealthGPT — privacy-first vs API-based humanization.
StealthGPT calls third-party LLM APIs to rewrite your text. SynthGuard runs the rewrite logic locally in your browser, with no API keys and no data leakage.
| Feature | SynthGuard | StealthGPT |
|---|---|---|
| Architecture | Pure browser-side TypeScript | API calls to LLM providers |
| Data exposure | None | Text sent to LLM provider |
| Speed | Sub-second for 5,000 words | Limited by API latency |
| Image humanization | Yes | No |
| Video humanization | Yes | No |
| Cost model | Flat €19/mo Pro | Token-based, scales with use |
| Languages | EN + DE native | EN primarily |
StealthGPT's approach is to use other LLMs as the humanizer — your AI text gets re-prompted through a chain of models that rewrite it in a more human voice. The output quality is good, but the architecture means your text travels through multiple third-party APIs and there's no way to know exactly what gets logged where.
SynthGuard's approach is algorithmic, not generative. Instead of asking an LLM to rewrite, the pipeline applies a sequence of deterministic layers (contractions, phrase-replace, restructure, punctuation, optional unicode) that target the exact signals AI detectors score. The result is faster, cheaper, and never leaves your browser.
Speed matters at scale. StealthGPT's API roundtrip puts a floor on processing time — even a fast LLM takes 1–3 seconds per paragraph. SynthGuard processes 5,000 words in under a second because there's no network roundtrip.
If you're a high-volume user (10,000+ words a day), the cost difference is significant. StealthGPT charges per token used; SynthGuard's Pro tier is flat at €19/month for 50 humanizations.
The image and video humanization features are exclusive to SynthGuard — StealthGPT is text-only.
Try SynthGuard — free account, no card required
Free tier: 3 credits per week. Pro: $14.99/mo for 50 credits, all camera profiles, video export and advanced controls.
Open the humanizerFrequently asked questions
Does StealthGPT use OpenAI under the hood?+
They use multiple LLM providers; the exact mix changes. Check their current docs.
Why is SynthGuard faster?+
No network calls. Everything runs as TypeScript in your browser tab.
Is the rewrite quality similar?+
Both work on current detectors. SynthGuard's deterministic approach is more predictable; StealthGPT's LLM approach can produce more varied outputs.
Can SynthGuard handle very long documents?+
Yes — there's no length cap because there's no API rate limit.
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