Free Tweet Preview & X Post Simulator
See how your post renders in X light and dark mode, with accurate 23-character t.co link counting and 280-character overflow highlights.
t.co URL & spacing rules applied
Every HTTP/HTTPS link on X is wrapped in a 23-character t.co link regardless of URL length. Standard accounts cap at 280 characters; X Premium allows longer posts with a "Show more" fold around 280 characters.
Characters past 280 highlight in red so you can tighten your hook before posting.
What does a tweet preview tool check?
A tweet preview tool renders your draft inside a realistic X feed card across light and dark modes while calculating X's exact 280-character limit, including the 23-character t.co URL rule. It lets you verify line spacing, hook punchiness, and truncation before publishing.
Unlike generic AI assistants that output clichéd platitudes, supapost applies proven patterns extracted from real top-performing social posts and replies. Use this free web tool for quick generation, or automate it in bulk using our REST API, n8n templates, and MCP server.
Example Outputs & Performance Patterns
Crawlable samples demonstrating high-engagement patterns vs generic filler.
Put this generation on autopilot
Every free generator is backed by supapost's REST API. Trigger posts and smart replies from Claude Code, n8n, Make, or custom cron scripts with your persistent brand voice applied.
curl -X POST https://supapost.ai/api/v1/content/generate \
-H "Authorization: Bearer sp_live_..." \
-H "Content-Type: application/json" \
-d '{
"type": "social",
"platform": "x",
"topic": "Why agentic workflows beat manual social scheduling"
}'How it works
Type or paste your X draft
Write your post and include any URLs. Links automatically count as 23 characters just like X's composer.
Inspect light & dark cards
Switch between light and dark X themes to verify spacing, readability, and 280-character overflow.
Publish or automate via API
Copy your polished post or generate daily X drafts automatically through supapost's REST API.
Frequently asked questions
How does X count URLs in a tweet preview?
X wraps every HTTP or HTTPS link in its t.co shortener, counting any link as 23 characters regardless of whether the original URL is 15 characters or 200 characters long. Our preview tool applies this exact 23-character rule automatically.
What is the X character limit in 2026?
Standard X accounts have a strict 280-character limit per post. X Premium subscribers can publish up to 25,000 characters, though feeds still truncate long posts around 280 characters behind a 'Show more' link.
Why check both light mode and dark mode before posting?
Over half of active X mobile users browse in dark mode. Checking both themes helps you spot dense paragraph blocks, awkward emoji contrast, and spacing issues before publishing.
Can I generate and validate 280-character X posts via API?
Yes. Calling POST /api/v1/content/generate with platform 'x' returns character-validated tweets and threads built on proven hook patterns, ready for n8n, Zapier, or Claude Code pipelines.
Explore related free tools
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AI Reply Generator
Smart RepliesWrite human-sounding X replies that earn profile visits and followers.
Ready to automate your social content?
Get 50 API requests per day, 1 workspace, and brand voice detection on the free plan.