Top 29 Line 21 Alternatives in 2026

AI Essay Checker spots AI‑generated content, grammar errors, and plagiarism in real time. It offers multilingual support, a rich text editor, and local processing for privacy, aiding students, teachers, writers, SEO pros, and legal professionals.

TextAdviser delivers AI‑powered language tools: grammar checking, plagiarism detection, syntactic analysis, fast text generation, rewriting, tone humanization, summarization, and name/title creation. It supports English, Spanish, Portuguese, Italian, French, and German for writers, students, marketers, and translators.

ParagraphAI offers real‑time grammar correction, one‑tap email drafting, and instant summarization of web pages and PDFs. It provides multilingual translation, customizable tone filters, a template library, and an instruction engine for repetitive tasks across mobile, desktop, and Chrome.

QuillBot is a writing and editing tool offering features such as paraphrasing, grammar and plagiarism checks, citation generation, and content creation assistance, all accessible through a Chrome extension or online platform.

LanguageTool is an AI grammar, spelling, and style checker supporting 30+ languages. It offers real‑time browser extensions, desktop and Word add‑ins, advanced Picky Mode, paraphrasing, and an API for developer integration.

Wordvice AI provides real‑time grammar checking, paraphrasing, translation, summarization, plagiarism and AI‑content detection, plus citation generation across multiple languages. It integrates with Chrome and Word, supporting students, researchers, professionals, teams, and offers on‑demand human editing.

AI Humanizer refines text by restructuring sentences to improve flow and reduce mechanical patterns while preserving meaning. It offers adjustable rewrite modes, selective paragraph editing, keyword protection, and built‑in AI detection and plagiarism checks.

AI Perfect Assistant adds ChatGPT, Gemini, Claude, and 60+ LLMs to Office 365 apps, delivering real‑time grammar, style checks, drafting, summarization, translation, and formula generation to streamline writing, analysis, and teamwork across Word, Excel, PowerPoint, Outlook, Teams, and OneNote.

The AI plagiarism checker from plagiarismcheck.org uses advanced AI technology to detect AI-generated content and plagiarism, supports various file formats, and is useful in academia, SEO, and recruitment.

AIText corrects grammar, spelling, and punctuation while paraphrasing to improve clarity. It enhances vocabulary and sentence structure, generating concise emails, articles, reports, essays, and social posts from brief prompts in over 20 languages. Ideal for students, marketers, and professionals.

ProWritingAid is an AI writing assistance tool that offers suggestions for grammar, style, and improvement with the touch of a button.

PerfectEssayWriter.ai creates structured, plagiarism‑free essays for high‑school to professional users. Set word count, essay type, academic level, tone, and citation style. Supports 27+ languages, real‑time research prompts, auto‑citation, live editing, and undetectable output.

Scribbr offers academic writing support with professional editing, plagiarism detection, citation generation across styles, AI‑powered proofreading, paraphrasing, summarizing, sentence rewriting, and a Chrome extension for in‑browser citations, helping students and researchers produce polished manuscripts.

Humanize AI Text rewrites AI‑generated drafts into natural, readable prose that passes AI detection tools with a 100% human score. It accepts PDF/DOCX uploads, preserves formatting, supports multiple languages, and lets users freeze keywords for SEO.

Humanize AI rewrites AI‑generated text into natural, human‑readable prose. It offers AI detection, plagiarism checking, grammar correction, paraphrasing, and an AI Writer. Its AI Article Agent creates keyword‑optimized content while maintaining readability for academics, marketers, and SEO writers.

AI Content Checker is a free browser extension that enhances web publishing by detecting errors, ensuring quality logic, and perfecting content before publication. It offers features like reviewing pages, answering specific questions, highlighting headings/links, identifying spacing issues, and opening links in new tabs for seamless content creation.

AI to Human Text Converter turns AI‑generated content into natural, human‑readable prose by removing AI signatures and improving flow and readability in multiple languages. Instantly rewrites drafts to sound conversational, bypassing AI‑detectors for writers, academics, and marketers.

The AI tool is a comprehensive content generation platform with various solutions to boost creativity and productivity including AI writer, copywriting, audio-to-text transformation, translation services, industry trends, AI chat, and brief writers.

WProofreader offers AI‑driven, multilingual spelling, grammar, and style checking for 20+ languages. It provides SDKs, an API, browser extensions, and CMS modules, with TLS encryption, GDPR compliance, on‑prem or AWS hosting, and customizable industry rules.

BookEdit is an innovative book editing solution that speeds up the modification process with advanced proofreading, paraphrasing, translation, and expansion features.

Auto Caption AI instantly generates subtitles in 99+ languages, preserving full HD 1080p/60 fps video quality. Editors can adjust fonts, colors, placement, and use ready‑made or custom templates, with one‑click emoji insertion to enhance captions.

AI Humanizer transforms AI‑generated text into natural prose with Basic, Aggressive, and Enhanced modes. It offers synonym suggestions, rephrase options, keyword locking, multi‑language support, and outputs grammar‑correct, low AI‑detector scores without registration.

Humanize AI transforms AI-generated text into human-sounding content, ensuring grammatical accuracy and readability. It supports multiple languages, making it suitable for academic writing, business reports, and creative projects while bypassing plagiarism detection.

AI Text Humanizer turns machine‑generated prose into natural, human‑readable text, removes repetitive patterns, offers readability scores, and supplies API and web interface with counters. It supports multiple languages, protects data, and assists students, writers, marketers, and corporate teams.

Humanize AI Text converts AI‑generated content into natural, human‑sounding prose while preserving meaning. It works browser‑free, supports unlimited words in multiple languages, and produces plagiarism‑free output that passes AI‑detection tools.

InstaText is an AI editing assistant that highlights suggestions for clarity, flow, word choice, and grammar. Users can accept or reject each change, select dialect, formality, or add custom terms. It works on Chrome, Gmail, Slack, Docs, Overleaf, and Word.

StealthWriter converts AI‑generated text into natural, human‑like content by correcting errors and odd phrasing across multiple languages. It includes an AI detector to confirm human likeness and supports models like ChatGPT, Claude, or Llama.

AHelp is an AI platform offering essay writing, paraphrasing, grammar and plagiarism checks, and AI source finding in multiple languages. It generates outlines, expands paragraphs, and validates originality, streamlining drafting and quality control.

Text Enhancer AI corrects grammar, rephrases, and restructures content in multiple languages. It offers plagiarism checks, tone adjustments, and alternative phrasing while preserving meaning. Users paste text, then receive a polished version within seconds.