Prices in GBP. Verified monthly. Always check the provider's site for the latest.
Pros & cons
Grammarly
Pros
+SOC 2 Type II and ISO 27001 certified — strongest compliance in the writing category
+Works across browser, desktop, Word, Google Docs, and email with one install
+Pro tier confirmed at £10/mo in GBP — transparent UK pricing
+Explicit opt-out from AI model training available in account settings
Cons
−Trains on user writing by default — opt-out required
−GDPR compliance not explicitly confirmed on accessed official pages
−Free AI prompt limit (100/mo) may feel restrictive for daily users
QuillBot
Pros
+Free tier paraphrases up to 125 words with no time limit
+9 paraphrase modes including Formal, Simple, Creative, and Expand
+Premium at £4/mo (annual) is the lowest price in the writing category
+Plagiarism checker and AI Detector bundled with Premium
Cons
−GDPR and SOC2 not confirmed from official sources
−Free tier capped at 125 words per paraphrase — limiting for longer content
−Focused on paraphrasing — not a full-document AI writing assistant
Our take— Grammarly wins
Based on our comparison of published pricing, features, and compliance data, Grammarly scores 8.1/10 to QuillBot's 7.3/10. Grammarly pulls ahead with SOC 2 certification and ISO 27001 certification. QuillBot counters with a no-training-on-your-data policy. Pick Grammarly if SOC 2 certification matters; pick QuillBot if a no-training-on-your-data policy matters.