Subject Line
The best 50 Subject Line AI tools - Free & Paid
Explore 50 AI for Subject Line
Subject Line Generator quickly produces ten tailored email subject lines. Users paste email content, pick a tone from nine categories, and optionally add emojis. Ideal for marketers, copywriters, and small businesses to boost open rates and accelerate copy creation.
Free
Mailmodo AI Subject Line Generator quickly creates email subject lines from a brief, allowing tone, intent, capitalization, emoji, and personalization adjustments. It supports multiple email types and customer journey stages, and tracks open, click‑through, unsubscribe, and spam metrics.
Subscription
- $39/mo
AI Email Writer uses OpenAI models to draft concise, persuasive emails. Users select preset prompts or create custom ones, then personalize with brand details. It suggests subject lines, edits tone, length, grammar, and translates into 36 languages.
Subscription
Mailscribe verifies email addresses, tests SMTP connections, and suggests subject lines. It runs client‑side without sign‑ups, keeping data private. Useful for marketers, copywriters, and technical teams to clean lists and boost open rates.
Free
LinePro uses AI to generate personalized email subject lines in seconds. Users set purpose, tone, and target demographics, and the tool delivers ten tailored options, helping marketers, sales teams, and small businesses improve open rates.
Free
An online image tool with features including background removal, image resizing, text addition, color palettes, conversion, and AI-powered social media bios, market slogans, business name ideas, and hashtag generation.
Free
Headline Studio uses AI to generate platform‑specific headlines and gives data‑driven feedback on word balance, character limits, and keyword relevance. It offers SERP previews, competitor comparison, a keyword explorer, thesaurus bank, favorites, and integration with CMS and email clients.
Freemium
- $4/mo
An all-in-one cloud toolkit for content creation, including picture editing, AI copywriting, video editing, and more.
Freemium
TheToolBus offers free, instant tools for small business owners, including PDF merge/split/compress, Word/Excel conversion, OCR, PowerPoint export, image compression/resizing/format conversion, background removal, QR code and website‑to‑PDF creation, plus business calculators and utilities like pass
Freemium
AI assistant for Apple Mail, Gmail, and Outlook that drafts, replies, summarizes, and corrects emails with GPT‑4o, extracts tasks for Mailbutler’s list, lets you fine‑tune tone and length, and stores data on EU servers for GDPR compliance.
Free trial
- $32.92/mo
Salesforge combines email and LinkedIn outreach, automating prospecting with AI personalization and an AI Sales Development Representative. It offers unlimited mailboxes, mailbox rotation, warm‑up, inbox monitoring, and integrations with CRMs, Zapier, Slack, Salesforce for streamlined pipeline manag
Free trial
- $48/mo
Smartlead is an AI‑driven cold‑outreach platform that unifies email, call, and SMS campaigns into one inbox. It automates warm‑ups, IP rotation, lead research, personalized messaging, CRM updates, and deliverability analytics to keep messages in primary inboxes.
Subscription
- $39/mo
Spark Mail unifies IMAP, iCloud, Exchange, Outlook, Yahoo, and Google accounts on one screen, featuring a Smart Inbox, Gatekeeper, and priority highlights. It offers AI summaries, drafting, translation, scheduling tools, and real‑time team collaboration, all encrypted on Google Cloud.
Subscription
Marketing Tool aggregates free utilities for marketing and web performance. It offers keyword research, backlink and SEO audits, social media scheduling, hashtag generation, ad‑budget calculators, speed testing, image compression, plagiarism checks, URL shortener, QR code. No registration required.
Free
TheToolBus offers free, no‑watermark PDF and image utilities for small business owners, including merge, compress, OCR, conversion, background removal, calculators, QR codes, and AI text extraction, all accessible without sign‑up.
Freemium
Clip Studio Paint offers natural brush strokes, over 100,000 customizable brushes, vector layers, 3D pose references, perspective rulers, onion‑skin animation up to 24 frames, and cloud sync across Windows, macOS, iPad, Android, and Chromebook.
Free trial
This product uses AI to personalize cold emails and LinkedIn messages for better conversion rates.
Paid
- $59/mo
Toolsaday is an AI platform offering text generation, email drafting, paraphrasing, story creation, and text‑to‑speech. It helps writers, marketers, students, and business professionals produce content quickly and customize models via an integrated developer hub.
Subscription
- $7.99/mo
Inbox Zero is an AI‑powered assistant for Gmail and Outlook that auto‑labels mail, drafts replies in the user’s voice, bulk unsubscribes, and syncs with calendars and CRM. It offers privacy‑centric, self‑hostable code and inbox analytics.
Subscription
- $18/mo
Maverick is an AI‑driven email marketing platform that optimizes inbox placement, auto‑generates and A/B‑tests subject lines, and delivers personalized videos, all integrating seamlessly with Klaviyo and major ecommerce CRMs to improve engagement and conversion rates.
Freemium
- $100/mo
GMass extends Gmail’s send limits and automates mass email campaigns with Google Sheets merges. It offers analytics, personalized templates, conditional logic, scheduled sequences, follow‑ups, list hygiene, A/B testing, SMTP and API integration for scalable outreach.
Freemium
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.
Free
Aiseo is an AI-powered free online tool that helps businesses generate catchy, memorable, and effective slogans in 25 different languages with various templates.
Free trial
ToolBaz offers 85+ free AI tools powered by GPT‑5, Claude, Gemini, Meta‑AI for content marketing, business communication, creative and academic writing, and technical documentation. Includes text‑to‑image, text‑to‑speech, intuitive, privacy‑focused interface.
Freemium
GhostWrite generates draft emails from concise prompts, offering subject‑line suggestions and template recognition. Users preview, edit, and approve drafts, while the system learns from edits to improve future suggestions. No auto‑sending; secure, lightweight web interface.
Freemium
Mailr is a Chrome extension that generates complete emails with a single click. Users specify an email goal and choose a tone, and the AI writes a full message, cutting drafting time for professionals.
Freemium
- $4.99/mo
AI‑powered InboxPro streamlines client acquisition and nurture workflows by auto‑composing, summarizing, and personalizing emails, automating multi‑step follow‑ups, syncing with Google Calendar, tracking opens and clicks, and providing analytics dashboards for data‑driven outreach.
Freemium
- $10/mo
SayHi is a Chrome extension that automates LinkedIn outreach by generating personalized messages from a contact’s profile. Users craft a one‑sentence template, choose tone, and can auto‑create templates from job descriptions or product details, with analytics and A/B testing.
Paid
- $10
MailMentor is a Chrome extension that scrapes webpages for contact data, stores it securely, and exports to CSV or webhooks. It builds AI‑generated email templates, integrates with Gmail, and tailors outreach using case studies.
Subscription
- $9/mo
PolitePost.net is a Microsoft Word add‑in that rewrites draft emails to improve tone, remove jargon, and fix grammar while preserving intent. It delivers polished versions in seconds, supports multiple style guidelines, and maintains data privacy.
Freemium
SummaLetter streamlines your overflowing inbox by consolidating multiple newsletters into a concise weekly digest using AI. Stay informed without the overwhelm, with the option for daily summaries. Seamless multi-language support included.
Freemium
SuperSend unifies cold‑email sequencing, mailbox management, and reply handling into one dashboard. It offers multi‑channel sequences, automated domain warm‑up, placement testing, AI‑based conversation threading, and deliverability analytics for B2B teams.
Freemium
- $99/mo
Topworksheets is an AI-powered tool that helps teachers create digital interactive worksheets and exercises for their students, saving time and enabling progress tracking.
Freemium
Forage Mail is a Gmail AI tool that filters distractions and prioritizes important emails with automatic labeling and daily summaries. It offers one-click unsubscribe, VIP lists, and multi-account support for a clutter-free inbox.
Free trial
- $8.25/mo
Shortwave is an AI‑powered platform that unifies email and future messaging tools, granting controlled read/write AI access to streamline drafting, filtering, and insight extraction, boosting daily workflow productivity across business teams.
Freemium
- $0.58/mo
Meet Alfred is a LinkedIn automation tool that facilitates multi-channel outreach with features like automated messaging, AI-driven lead finding, a centralized inbox, and performance tracking, aimed at enhancing lead generation and improving conversion rates.
Free trial
TubeBuddy streamlines YouTube workflow with keyword research, SEO tools, thumbnail generation, content strategy analytics, A/B testing, bulk editing, and end‑screen management, helping creators optimize visibility and scale production efficiently, and channel growth.
Paid
- $3.75/mo