Complete guide to free APIs every startup needs: PDF processing, email validation, QR codes, invoicing, AI text tools, and more. One API key for 13 services.
Startups move fast. Every hour spent building commodity infrastructure — PDF generation, email validation, QR codes, currency conversion — is an hour not spent on your core product. In 2026, the smartest startups use free APIs to handle these common features and focus their engineering time on what makes them unique.
This guide covers 13 free APIs that every startup needs, all available with a single API key and zero upfront cost.
Here is a complete set of utility APIs that cover the most common needs for web and mobile startups. All 13 APIs share a single API key with 100 requests/day on the free tier:
| Category | API | Key Features |
|---|---|---|
| Documents | PDF Toolkit | Merge, split, compress, watermark, extract text, add page numbers |
| Billing | Invoice Forge | Generate professional PDF invoices with logos, tax, line items |
| Verification | Email Validator | DNS/MX checks, disposable detection, typo suggestions |
| Audio | Text-to-Speech | 300+ neural voices, 70+ languages, MP3 output |
| Geolocation | IP Geolocation | Country, city, ISP, timezone from any IP address |
| Finance | Currency Exchange | 31+ currencies, real-time rates, historical data from ECB |
| Crypto | Crypto Prices | 10,000+ coins, real-time prices, charts, trending data |
| Marketing | QR Code Generator | 6 styles, PNG/SVG/base64, custom colors, batch generation |
| Media | Image Generation | Placeholders, social cards, OG images, avatars, gradients |
| Capture | Screenshot API | Full-page website screenshots, custom viewport, headless Chrome |
| AI | AI Text Tools | Summarize, translate, rewrite, sentiment, keyword extraction |
| Utilities | DevTools | Hash, UUID, Base64, JWT decode, regex test, password gen |
| Links | URL Toolkit | Shorten, expand, metadata, redirects, click tracking |
Every SaaS application eventually needs to handle PDFs — merging contracts, compressing uploads, extracting text for search indexing, or adding watermarks. Building PDF processing in-house means dealing with libraries like PyMuPDF, Ghostscript, or pdf-lib, each with their own quirks.
The PDF Toolkit API handles all of this with simple REST endpoints. Upload files, get results. Supports merge, split, compress, rotate, watermark, text extraction, metadata, password protection, image-to-PDF conversion, and page numbering.
If your startup bills customers, you need invoices. The Invoice Forge API generates professional PDF invoices from JSON data. Send company details, client info, line items with quantities and prices, tax rates, and discounts. Get back a production-ready PDF invoice.
Bad email addresses cost startups money — failed deliveries, damaged sender reputation, wasted marketing spend. The Email Validator API checks syntax, performs DNS/MX lookups, detects disposable email providers, and suggests corrections for common typos (like "gmial.com" → "gmail.com").
Building an accessibility feature? Creating audio content? The Text-to-Speech API converts text to natural-sounding speech with 300+ neural voices in 70+ languages. Perfect for podcast tools, language learning apps, accessibility features, and IVR systems.
Know where your users are. The IP Geolocation API returns country, city, timezone, ISP, and connection type from any IP address. Use it for content localization, fraud detection, geo-targeted marketing, and analytics enrichment.
Selling internationally? The Currency Exchange API provides real-time exchange rates for 31+ currencies from the European Central Bank. Convert amounts, list all rates, access historical data.
Building anything in the crypto or fintech space? The Crypto Price API covers 10,000+ coins with real-time prices, market cap, volume, 24h changes, historical charts, and trending coins.
The QR Code API generates customizable QR codes in 6 styles with custom colors. Output as PNG, SVG, or base64. Perfect for payment pages, event tickets, product packaging, and marketing materials.
The Image Generation API creates placeholder images, social media cards, Open Graph images, avatars, badges, gradients, color palettes, and geometric patterns. No design tools needed — generate images programmatically.
The Screenshot API captures full-page screenshots of any website using headless Chrome. Use it for monitoring dashboards, generating link previews, archiving web pages, and automated testing.
The AI Text Tools API provides AI-powered text processing: summarization, translation, rewriting, sentiment analysis, and keyword extraction. Powered by local AI models — your data is never sent to third parties.
The DevTools API provides 26+ utility functions that every developer needs: hash generation (MD5, SHA-256), UUID creation, Base64 encoding/decoding, JWT decoding, regex testing, password generation, Lorem Ipsum, and more.
The biggest advantage of the DevProToolkit platform is unified access. Instead of managing 13 different API accounts, credentials, and billing relationships, you get a single API key that works across all services. One signup, one key, one dashboard.
# The same API key works for every service
curl "https://api.commandsector.in/api/qr/generate?data=hello" -H "X-API-Key: YOUR_KEY"
curl "https://api.commandsector.in/api/email/validate/test@example.com" -H "X-API-Key: YOUR_KEY"
curl "https://api.commandsector.in/api/crypto/price/bitcoin" -H "X-API-Key: YOUR_KEY"
curl "https://api.commandsector.in/api/currency/convert/100/USD/EUR" -H "X-API-Key: YOUR_KEY"| Feature | Build In-House (Est. Hours) | API Integration (Est. Hours) | Savings |
|---|---|---|---|
| PDF merge/split/compress | 16-24h | 1-2h | 90% |
| Email validation + disposable detection | 8-16h | 0.5h | 95% |
| QR code generation (6 styles) | 12-20h | 0.5h | 96% |
| Text-to-speech (300+ voices) | 40h+ | 1h | 97% |
| IP geolocation database | 8-12h | 0.5h | 94% |
| Currency exchange rates | 4-8h | 0.5h | 90% |
| Invoice PDF generation | 20-30h | 1-2h | 93% |
| Total | 108-150h | 5-7h | 95% |
At an average developer rate of $100/hour, using APIs instead of building in-house saves $10,000-$15,000 in development cost for a typical startup MVP.
Yes. The free tier includes 100 requests/day per API with no credit card required. This is enough for development, testing, and small production workloads. Pro plans are available for higher volumes.
Absolutely. All APIs are production-ready with consistent uptime, error handling, and rate limiting. Many startups use the free tier for their initial launch and upgrade to Pro as they scale.
Requests beyond your daily limit receive a 429 status code. Your service continues to work normally the next day when limits reset. Upgrade to Pro for 10,000 requests/day.
No. One API key gives you access to all 13 APIs. This is a key advantage of the DevProToolkit platform over using separate API providers.
Any language that can make HTTP requests: Python, JavaScript, Go, Ruby, PHP, Rust, Java, C#, Swift, Kotlin, and more. We provide code examples in Python, JavaScript, and cURL.
Get your free API key and start making requests in minutes.
curl "http://147.224.212.116/api/..." \
-H "X-API-Key: YOUR_API_KEY"Get a free API key with 100 requests/day. No credit card required.
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