Social Media Ad Builder Docs

AI-powered ad copy generation for 8 social platforms. Pick a platform, enter your business details, choose your AI model, and get production-ready ad copy tailored to each network's format, character limits, and best practices.

🔐 Privacy First This tool runs entirely in your browser. Your API keys are AES-256 encrypted in sessionStorage and never sent to any server other than your chosen AI provider's API. Zero server calls.

Supported Platforms

Platform	Ad Formats	Key Constraint
Meta (Facebook/Instagram)	Feed, Stories, Reels	Primary text 125 chars
LinkedIn	Sponsored Content, Message Ads	Intro text 150 chars
X (Twitter)	Promoted Tweets, Cards	Tweet text 280 chars
YouTube	In-stream, Bumper, Discovery	Format-dependent
TikTok	In-Feed, TopView	Ad text 100 chars
Pinterest	Standard Pins, Idea Pins	Description 500 chars
Snapchat	Snap Ads, Story Ads	Headline 34 chars
Threads	Sponsored Posts	Thread text 500 chars

Who It's For

The Social Media Ad Builder is designed for paid media specialists, social media managers, small business owners, and marketing agencies who need to produce high-quality ad copy across multiple social platforms quickly — without switching between platform-specific tools or memorizing every character limit.

Media buyers running campaigns across Meta, LinkedIn, X, TikTok, and more
Small business owners who need professional ad copy without hiring a copywriter
Agencies producing ad creative for multiple clients across platforms
Content creators promoting products, courses, or services on social media

AI Configuration

Recommended: Click "Sign in with Google" for Buddy credits — one sign-in works across all tools. Or bring your own API key from any provider:

Google Gemini

choose one

Get your key at aistudio.google.com/apikey. Starts with AIzaSy. Generous free tier — great for testing and regular use. Sign in with any Google account, click "Create API key", and copy it. No billing setup required for the free tier.

Anthropic Claude

choose one

Get your key at console.anthropic.com/settings/keys. Starts with sk-ant-api03-. Create an account → go to Settings → API Keys → "Create Key". New accounts get $5 in free credits. Add a billing method after credits are used.

OpenAI GPT

choose one

Get your key at platform.openai.com/api-keys. Starts with sk-proj-. Create an account → go to API Keys → "Create new secret key". Requires a paid account with billing enabled. Copy the key immediately — it won't be shown again.

⚠️ Key Security Your key is used for a single direct API call from your browser to the provider. It is never proxied through any server. The key is encrypted in sessionStorage — closing the tab destroys it. We recommend using keys with restricted permissions (rate limits, spend caps) as a best practice.

Supported Models

Provider	Model	Speed	Quality	Cost
Google	Gemini 3 Flash	Very Fast	Good	Free tier
Google	Gemini 3 Pro	Medium	Very Good	Free tier
Anthropic	Claude Sonnet 4.6	Medium	Excellent	~$0.003/run
Anthropic	Claude Opus 4.6	Slower	Best	~$0.015/run
OpenAI	GPT-5.2	Medium	Excellent	~$0.005/run
OpenAI	GPT-5.2 Pro	Slower	Best	~$0.020/run

Estimated costs are per generation (~2,000 input tokens + ~1,500 output tokens). Actual costs depend on prompt length and model pricing at time of use.

💡 Model Recommendation Start with Gemini 3 Flash for fast iteration on the free tier. Move to Claude Sonnet 4.6 or GPT-5.2 when you need more nuanced, platform-specific copy. Opus and Pro models are best for complex B2B campaigns or when tone precision is critical.

Meta (Facebook/Instagram)

Meta ads span Facebook Feed, Instagram Feed, Stories, and Reels. The builder generates copy optimized for feed placements where text is most visible, while keeping it punchy enough for Stories overlays.

Element	Character Limit	Notes
Primary Text	125 chars	Main ad copy shown above the creative. Text beyond 125 chars is truncated behind "See more".
Headline	40 chars	Bold text below the creative. Keep it action-oriented.
Description	30 chars	Secondary text below the headline. Not always shown — treat as optional reinforcement.
Link Description	30 chars	Appears in the link preview area. Reinforce the CTA or add urgency.

💡 Meta Best Practices Lead with the hook in the first line — most users won't tap "See more". Use social proof ("Join 10,000+ marketers"), specific numbers ("Save 40%"), and direct CTAs ("Shop Now", "Get Started Free"). Avoid walls of text; the algorithm favors concise primary text in feed placements.

LinkedIn Ads

LinkedIn ads target professionals, so the tone skews business-oriented. The builder generates copy suited for Sponsored Content (single image and carousel) and adapts language for a B2B audience.

Element	Character Limit	Notes
Intro Text	150 chars	The main text above the creative. Up to 600 chars are allowed, but only ~150 show before "see more".
Headline	70 chars	Bold text below the image. Longer headlines are truncated on mobile.
Description	100 chars	Appears below the headline in desktop feed. Optional on mobile.

💡 LinkedIn Best Practices Speak to the professional outcome — career growth, revenue impact, efficiency gains. Name the job title or industry when possible ("For VP-level marketers at SaaS companies"). LinkedIn audiences respond to thought leadership framing over hard-sell language. Use "Learn more" or "Download" CTAs over "Buy now".

X (Twitter)

X ads are built around the tweet format — concise, conversational, and fast. The builder generates promoted tweet copy and Website Card headlines optimized for the timeline scroll.

Element	Character Limit	Notes
Tweet Text	280 chars	The main promoted tweet. Links consume ~23 chars. Keep the core message under 257 chars if including a URL.
Card Headline	70 chars	Shown on the Website Card below the tweet. Should complement, not repeat, the tweet text.

💡 X Best Practices Write like a human, not a brand. Tweets that feel native to the timeline outperform polished ad copy. Use line breaks for readability. Ask questions to drive engagement. Hashtags are optional — one or two relevant ones at most. Avoid hashtag-stuffing.

YouTube Ads

YouTube supports multiple video ad formats, each with different text overlay and companion requirements. The builder generates companion text for three primary formats:

Format	Duration	Text Elements	Notes
In-Stream (Skippable)	Any length	Companion banner headline, description, display URL	Viewers can skip after 5 seconds. The companion banner drives clicks after skip.
Bumper	6 seconds	Overlay text, companion headline	Non-skippable. The copy must deliver one sharp message in under 6 seconds.
Discovery	Any length	Headline (100 chars), Description line 1 (35 chars), Description line 2 (35 chars)	Appears in search results and sidebar. Think of it like a search ad — the headline sells the click.

💡 YouTube Best Practices For in-stream, front-load your value prop in the first 5 seconds — that's all you get before skip. Bumper ads should focus on a single memorable message or brand impression. Discovery ads compete with organic thumbnails, so write headlines that spark curiosity.

TikTok Ads

TikTok ads appear in the For You feed and must feel native to the platform. The builder generates short, punchy ad text and CTA variations designed for a mobile-first, sound-on audience.

Element	Character Limit	Notes
Ad Text	100 chars	Appears below the username. Truncated aggressively on smaller screens — front-load the message.
CTA Text	Varies	Button text like "Shop Now", "Learn More", "Download". Choose from TikTok's CTA library or write custom.

💡 TikTok Best Practices Don't make ads — make TikToks. The copy should feel casual, authentic, and platform-native. Use language your audience actually uses. Emojis work well. Pair the ad text with a strong visual hook in the first 1-2 seconds of the video.

Pinterest Ads

Pinterest is a visual discovery engine. Ads look like organic Pins, and users are in a shopping and planning mindset. The builder generates Pin titles and descriptions optimized for search and discovery.

Element	Character Limit	Notes
Pin Title	100 chars	The main title shown on the Pin. Include relevant keywords — Pinterest search is keyword-driven.
Pin Description	500 chars	Longer-form description with room for detail. Include keywords naturally, describe the value, and add a CTA.

💡 Pinterest Best Practices Think SEO. Pinterest is a search engine as much as a social platform. Use descriptive, keyword-rich titles ("Modern Farmhouse Kitchen Ideas — Under $500"). Descriptions should paint a picture and include natural keywords. Seasonal content (holiday gifts, summer recipes) performs especially well.

Snapchat Ads

Snapchat ads are full-screen, mobile-only, and ephemeral-feeling. The builder generates tight headlines and brand-forward copy for Snap Ads and Story Ads.

Element	Character Limit	Notes
Ad Name	255 chars	Internal name for the ad (not shown to users). Use for campaign organization.
Headline	34 chars	The primary text overlay. Extremely tight — every word must earn its place.
Brand Name	25 chars	Shown at the top of the ad. Use your brand or product name.

💡 Snapchat Best Practices 34 characters is brutal — write the shortest possible version of your value prop. Use action verbs ("Get", "Try", "Save"). Snapchat's audience is young (13-34), so match the tone accordingly. Avoid corporate language entirely.

Threads Ads

Threads is Meta's text-first social platform. Ads appear as sponsored posts in the feed and should feel like native Threads posts — conversational, opinionated, and text-forward.

Element	Character Limit	Notes
Thread Text	500 chars	The main post text. Threads supports longer-form text than X, so you have room to develop a thought.

💡 Threads Best Practices Write like you're posting on your own feed. Threads rewards authenticity and conversation-starters. Take a stance, share an opinion, or ask a thought-provoking question. The best Threads ads don't look like ads — they look like posts from a smart friend.

Workflow — Step by Step

Five steps from zero to production-ready social ad copy:

Choose Your Platform

Select one of the 8 supported platforms from the dropdown. The builder adjusts its prompt, character limits, and output format to match the platform's ad specifications.

Enter Business Details

Provide your business name, what you're promoting, your target audience, and any specific value propositions or offers. The more detail you give, the sharper the output.

Sign In or Select AI Model

Click Sign in with Google for Buddy credits (25 free, universal across all tools). Or expand "Advanced: Use your own API key" to choose a provider and paste your key — encrypted with AES-256-GCM, sessionStorage only.

Generate Ad Copy

Hit "Generate" and the AI creates a full set of ad copy tailored to your chosen platform's formats, character limits, and best practices. Generation typically takes 3-8 seconds depending on the model.

Review, Copy & Export

Review each generated element with its character count. Copy individual items, copy all at once, or export the full set. Run the builder again with tweaked inputs for more variations.

💡 Iteration is the strategy Don't stop at one generation. Run the builder 2-3 times per platform with slightly different business descriptions or target audiences, then cherry-pick the best elements from each batch. Try different AI models for variety.

Tips & Best Practices

💡 Be specific about your audience "Small business owners in the US" is fine. "Female founders running DTC ecommerce brands doing $1-5M revenue" is much better. The AI writes sharper copy when it knows exactly who it's talking to.

💡 Include your unique selling proposition Tell the AI what makes you different. "We're 60% cheaper than Salesforce", "Only organic ingredients", "Built by former Google engineers" — specifics beat generics every time.

💡 Mention your current offer If you're running a promotion, discount, or limited-time offer, include it in the business details. "20% off with code SPRING" or "Free trial, no credit card required" gives the AI concrete CTAs to work with.

💡 Try different models for the same brief Claude tends toward precise, structured output. GPT generates more creative variations. Gemini is the fastest and works well for quick iteration. Use all three and mix the best results.

💡 Match the platform's native tone The builder adjusts tone per platform, but your input matters too. Describe your brand voice — "professional but approachable" for LinkedIn, "casual and fun" for TikTok, "bold and direct" for X. The AI follows your lead.

💡 Use the output as a starting point AI-generated copy is a strong first draft, not the final product. Edit for your brand voice, check that claims are accurate, and A/B test multiple variants. The builder saves you 80% of the writing time — spend the remaining 20% on polish.

Privacy & Security

The Social Media Ad Builder uses a defense-in-depth approach to protect your API keys:

Web Crypto API Encryption (AES-256-GCM)

When you enter an API key, the browser generates a random 256-bit encryption key using crypto.subtle.generateKey(). Your API key is encrypted with this key using AES-GCM mode with a random 12-byte IV. The encrypted ciphertext is stored in sessionStorage — the plaintext API key is never stored anywhere.

Session-Only Storage

Both the encryption key and the encrypted API key are stored in sessionStorage, not localStorage. sessionStorage is scoped to the browser tab and is automatically cleared when the tab is closed. It doesn't persist across sessions, isn't shared between tabs, and can't be accessed by other sites.

Direct API Calls (No Proxy)

API calls go directly from your browser to the AI provider's endpoint. The request never passes through any intermediary server. The builder is a static HTML file — there is no backend to intercept traffic. Zero server calls.

Manual Clear

The "Clear Session" button in the app immediately calls sessionStorage.clear(), destroying both the encryption key and the encrypted API key. This is irreversible.

🔍 Verify It Yourself The entire tool is a single HTML file. Right-click → View Source and you'll see every line of code. There are no hidden endpoints, no analytics, no tracking pixels, no external scripts (beyond Google Fonts and GTM for analytics).

Troubleshooting

API Key Not Working

Symptoms

Error message mentioning "401", "unauthorized", or "invalid API key" after clicking Generate.

Check the key format — Gemini keys start with AIzaSy, Claude keys with sk-ant-api03-, OpenAI keys with sk-proj-.
Make sure you copied the full key — trailing spaces or truncated keys are a common cause.
Verify the key is active — go to your provider's dashboard and confirm the key hasn't been revoked or expired.
Check provider selection — make sure the selected provider matches the key you entered (e.g., don't paste a Gemini key with Claude selected).

Rate Limits

Symptoms

Error message mentioning "429", "rate limit", or "too many requests".

Wait and retry — most rate limits reset within 60 seconds.
Gemini free tier — limited to 15 requests per minute and 1,500 per day. Space out your generations.
Claude/OpenAI — rate limits depend on your account tier. New accounts start with lower limits that increase over time.
Switch models — if one provider is rate-limited, try generating with a different one while you wait.

Empty or Incomplete Output

Symptoms

The builder returns blank fields, partial results, or garbled text.

Add more detail — vague business descriptions produce vague output. Include your product name, audience, offer, and differentiator.
Try a different model — some models handle specific platforms better than others. If Gemini gives incomplete results, try Claude or GPT.
Regenerate — AI output varies between runs. A second generation with the same inputs often produces better results.
Check your internet connection — the browser makes a direct API call to the provider. A dropped connection mid-stream can cause incomplete output.

Browser Compatibility

Symptoms

The app doesn't load, encryption fails, or the UI looks broken.

Use a modern browser — Chrome 90+, Firefox 90+, Safari 15+, or Edge 90+. The tool requires the Web Crypto API and modern JavaScript features.
Disable ad blockers temporarily — some ad blockers interfere with direct API calls to AI providers.
Clear sessionStorage — open DevTools → Application → Session Storage and clear the entries for this site, then reload.

⚠️ Still stuck? Open your browser's DevTools console (F12 → Console tab) and look for red error messages. The error details will usually tell you exactly what went wrong — whether it's a network issue, an API error, or a browser compatibility problem.