Vetted full stack & backend engineers capable of delivering Landing Page solutions
Khmelnytskyi, Ukraine
Full-Stack Developer, Fractional CTO — Websites, Apps, Servers, Databases, AI, SEO & QA
Full-stack developer working across the entire stack — websites, apps, servers, databases, AI integrations, SEO, and QA. Languages & Core: writes code in JavaScript, TypeScript, Python, PHP, Go, and Rust. Architects scalable systems for large-scale projects. Frontend & Interfaces: builds websites and web applications with React and Next.js. Crafts responsive interfaces with Tailwind CSS, Radix UI and Shadcn, adds smooth animations with Framer Motion, and interactive charts with Recharts. SEO Audit & On-Page Optimization: semantic keyword research, resolving technical indexing issues, and optimizing page load speeds. Structures page architecture, meta tags, and multi-language support (i18n). Copywriting & Content Strategy: writes technical articles, drafts precise content briefs for writers, and develops content plans. QA & Testing: full-cycle testing for websites, web services, and Android apps — manual QA for UI/UX and business logic, plus automated testing with Jest, Vitest, Playwright and E2E. Backend, Cloud & Databases: complex API integrations of any scale. Builds servers with Node.js (Express, Fastify). Works with PostgreSQL, MySQL and MongoDB, ORMs (Prisma, Drizzle), and cloud infrastructure (Supabase, Firebase, Cloudflare). Browser Extensions & Automation: develops Manifest V3 browser extensions for Chrome, Edge, Firefox and other browsers. Builds web scrapers for complex data extraction using Puppeteer and Playwright. AI & Intelligent Agents: builds custom AI agents and integrates LLMs from OpenAI, Google Gemini, and Anthropic Claude via API, including Claude Code setups. Servers & DevOps: Linux (Ubuntu) and VPS administration — setup, updates, real-time monitoring, secure process isolation, Nginx, PM2, and CI/CD deployment via GitHub Actions. Telegram Bots: develops advanced Telegram bots (Telegraf, Grammy) integrated with AI, payment gateways, Google Sheets, and crypto exchanges. Desktop Applications: builds cross-platform software for Windows and macOS using Electron and Rust. Additional expertise: site development and customization with WordPress and Astro.
AI & Distributed Systems Architect | Enterprise AI, RAG, Cloud, Blockchain | Advisory & Fractional Leadership
AI and distributed systems architect providing advisory and fractional leadership on enterprise AI, RAG pipelines, cloud architecture and blockchain-backed data systems.
Khmelnytskyi, Ukraine
Senior Backend Engineer | AI Engineering | PHP, Python, LLM Applications
Senior backend engineer working across PHP and Python, with a growing focus on AI engineering: building LLM-powered application features on top of existing backend systems and APIs.
CTO & Founder at Punch AI | Building Software Harnesses for AI-Powered Development | PhD Student in Software Engineering
CTO and Founder at Punch AI, building software harnesses that make AI-powered development safer and more reliable. PhD student in Software Engineering, bridging applied AI engineering with academic research.
Digital marketing and design agencies routinely charge $150 to $250 per hour or quote fixed packages between $5,000 and $20,000 for landing page projects. Within that agency model, projects pass through account coordinators, junior copywriters, and creative directors for six to ten weeks before reaching an engineer. The resulting deliverable is often a bloated WordPress or Webflow theme weighed down by dozens of third-party plugins that take four seconds to render on mobile networks.
Conversely, hiring budget marketplace freelancers frequently yields generic template copies with zero conversion discipline, broken mobile viewports, and missing analytics tags. Working directly with an independent senior landing page engineer on ProofDevs resolves this compromise. At transparent rates between $45 and $95 per hour, you partner with an engineer who writes clean code in Next.js or Astro, tests forms against live payment and CRM APIs, and delivers verified sub-second mobile load profiles within seven to fourteen days.
| Evaluation Factor | Digital Design Agency | Budget Freelance Marketplace | ProofDevs Independent Senior Engineer |
|---|---|---|---|
| Typical Cost Band | $5,000 – $20,000 per project | $50 – $300 fixed price | $45 – $95 / hr (typically $1,200 – $3,500 total) |
| Turnaround Time | 6 to 12 weeks of bureaucratic revisions | 2 to 5 days (template copy-paste) | 7 to 14 business days (production-ready) |
| Core Web Vitals Discipline | Poor (heavy page builders, 3MB bundles) | Unchecked (crashes on low-end mobile) | Strict: 95+ Lighthouse score, sub-1.2s LCP |
| Analytics & Tracking Setup | Billed as separate agency upsell ($2k+) | Missing or broken generic script tag | Included: GA4, GTM, and Meta CAPI verified at build |
| Conversion Accountability | Vanity aesthetic awards, no lead math | Zero accountability for performance | Direct alignment with cost per acquisition (CPA) targets |
| Code & Platform Ownership | Proprietary builder lock-in or monthly fees | Often unversioned zip archives | 100% client-owned Git repository & hosting account |
Mobile loading velocity directly dictates conversion acquisition efficiency. Industry benchmarks confirm that mobile visitor drop-off increases by 32% as page load duration lengthens from 1 second to 3 seconds. Visual builders such as Elementor, Divi, and Unbounce inject dozens of render-blocking stylesheets, uncompressed visual assets, and deeply nested DOM trees that delay Largest Contentful Paint (LCP) and degrade Interaction to Next Paint (INP). A senior landing page developer structures component trees in Next.js, Astro, or Tailwind CSS, ensuring the critical rendering path executes in under 800 milliseconds on standard 4G mobile connections.
Eliminating conversion leakage and layout instability requires rigorous structural discipline. A landing page exists for a single commercial outcome: guiding the visitor across the primary call-to-action threshold. Navigation menus with external links, distracting header banners, and complex multi-column footers leak paid traffic away from the conversion funnel. Furthermore, Cumulative Layout Shift (CLS) caused by late-loading fonts, unreserved image dimensions, or third-party chat popups displaces buttons while visitors are actively tapping, causing immediate mobile user frustration.
Executing conversion rate optimization (CRO) at scale requires server-rendered A/B testing rather than client-side script manipulation. Legacy visual testing tools like Google Optimize or client-side VWO hide page contents until JavaScript executes, creating an unstyled flash or prolonged white screen that depresses user trust. Senior engineers implement server-side traffic splitting using edge middleware (such as Vercel Edge Middleware or Cloudflare Workers) to serve pre-rendered HTML variants with zero visual flicker and zero latency penalty.
Senior landing page developers construct pages using tools optimized for compilation speed, bundle minimization, and responsive behavior. The standard development stack combines Next.js (utilizing React Server Components), Astro for zero-JS static publishing, Tailwind CSS for atomic utility styling, and Zod for serverless form validation. Incompetent developers frequently introduce bloated animation libraries, bulky UI kits, and multiple client-side analytics scripts that flood the browser main thread.
Qualified engineers treat performance as an absolute constraint. They load web fonts locally with font-display swap, generate responsive WebP and AVIF image formats with explicit width and height containers, and defer non-critical analytics beacons until after user interaction.
Architecture Rule: Zero Third-Party Script Execution on Critical Render Path
Never load third-party marketing pixels, session replays (Hotjar, Microsoft Clarity), or live chat widgets synchronously inside the document head. Scripts must execute asynchronously or defer until after the primary Largest Contentful Paint (LCP) event fires. Loading uncurated tracking scripts blocks main-thread JavaScript execution, transforming a 90+ Lighthouse performance baseline into an unresponsive 45 score on mobile devices.
Landing page development engagements span emergency speed optimizations, custom sales funnel builds, and complex multi-step calculators. Establishing realistic engineering hour ranges provides founders and marketing leads with clarity for budgeting and campaign scheduling.
Delivery speed is driven by copy readiness, visual asset preparation, and external CRM API documentation. A senior engineer divides execution into clear, sequential milestones.
Independent landing page developers on ProofDevs set transparent hourly rates between $45 and $95 per hour based on full-stack architecture background, conversion rate optimization experience, and headless CMS integrations. Compared to marketing agencies billing $150 to $250 per hour, this direct model reduces development expenditure by 60%.
The commercial return on investment for high-performance landing page development is rooted in conversion arithmetic. For instance, if an advertising campaign directs 5,000 monthly visitors to a page with a 2.0% conversion rate at $80 cost per acquisition (100 conversions for $8,000 ad spend), lifting the conversion rate to 3.5% yields 175 conversions while cutting cost per acquisition to $45.71. That produces 75 additional customers every month from the identical ad spend. An initial development investment of $1,500 to $3,500 pays for itself within the first 30 to 60 days of live traffic.
Clients retain 100% legal ownership of all source code repositories, visual assets, deployment scripts, and cloud hosting accounts upon milestone completion. You are never bound to agency-controlled CMS subscriptions or locked into proprietary website builders.
Four technological foundations dominate commercial landing page delivery: Next.js with Tailwind CSS for unified full-stack web applications, Astro for content-focused zero-JS static output, WordPress with custom themes for marketing teams that demand daily visual editing, and visual SaaS builders (Webflow, Unbounce) for rapid prototyping. Next.js represents the standard choice for paid advertising funnels because static pre-rendering delivers sub-second page loads while React supports rich interactive calculators and dynamic pricing tables.
Astro offers an exceptional solution for editorial and documentation-adjacent funnels where client-side JavaScript can be stripped completely, reducing page payload sizes to under 50 kilobytes.
| Platform / Stack | Mobile Load Speed (LCP) | Hosting & Maintenance Cost | Marketing Editor Access | Recommended Application |
|---|---|---|---|---|
| Next.js + Tailwind CSS | Sub-1.0 second (Static Export) | $0 – $20 / month (Vercel) | Requires headless CMS or Git PR | High-spend paid advertising campaigns, SaaS product launches, custom interactive calculators |
| Astro + Vanilla / Tailwind | Sub-0.8 second (Zero Client JS) | $0 / month (Cloudflare / Netlify) | Requires markdown or headless CMS | Content-heavy landing pages, developer tools, documentation-adjacent sales funnels |
| WordPress + Custom Theme | 1.5 – 3.0 seconds (Server-rendered) | $15 – $60 / month (Managed VPS) | Direct Gutenberg visual editing | Marketing teams requiring daily copy edits within an existing WordPress ecosystem |
| Visual Builders (Webflow/Unbounce) | 2.0 – 4.5 seconds (Heavy JS bundle) | $29 – $120 / month (Per workspace) | Drag-and-drop visual interface | Short-lived event promotions, early hypothesis validation before engineering investment |
Marketing teams operating on visual page builders inevitably encounter structural bottlenecks: slow mobile load speeds exceeding three seconds, rigid responsive layout boundaries, and recurring platform subscription fees ($99 to $299 per month). These builder platforms output sprawling DOM trees with thousands of redundant wrapper divs and unoptimized script tags that fail Core Web Vitals audits.
A senior landing page developer executes migrations systematically without compromising existing search engine rankings or advertising campaign tracking. The engineer audits existing high-performing copy, extracts brand typography and palette tokens, reconstructs the layout using modular React and Tailwind CSS components, and configures automated form endpoints with Turnstile bot verification. DNS transitions execute with zero downtime and strict URL mapping.
When inheriting an underperforming landing page codebase, a senior engineer conducts an objective diagnostic audit before proposing modifications. In 2 to 4 hours, the audit analyzes synthetic Lighthouse performance data, inspects real-user Core Web Vitals metrics in Google Search Console, tests form submission error boundaries, and reviews Google Tag Manager event firing sequences.
A complete code rewrite is recommended only when an existing page relies on an unmaintained legacy framework, outputs severe DOM errors that crash mobile browsers, or carries security vulnerabilities in form handling. In standard scenarios, a senior engineer optimizes visual assets, refactors blocking scripts, and rectifies mobile responsive defects within 6 to 14 hours.
Audit Rule: Inspect Mobile Form Abandonment Points in Session Recordings
Never redesign a landing page based solely on aesthetic preference. A senior landing page developer evaluates session recordings and form analytics to isolate exact abandonment triggers: form input field errors, unhelpful validation alerts, unexpected mobile keyboard obstructions, or layout jumps that displace the submit button during payment processing.
Senior landing page developers demonstrate competence through disciplined engineering choices: they explain how to eliminate Cumulative Layout Shift (CLS) using CSS aspect ratios, implement serverless form validation with Zod, and structure semantic HTML tags (<main>, <section>, <form>) for accessibility and search crawler comprehension. Incompetent candidates build desktop-only layouts, introduce heavy jQuery parallax scripts that trigger mobile stutter, or fail to handle network error states during form submissions.
A paid 3-to-5-hour practical trial provides conclusive validation of engineering capability. Supply the candidate with a Figma layout slice for a hero section and lead capture form. Ask the candidate to code a responsive React and Tailwind component featuring client-side schema validation, accessible keyboard navigation, and a sub-1.2s mobile load profile.
You will receive matches with two to four available senior landing page developers within 2 to 4 hours of submitting your page URL, design assets, and campaign goals.
Hourly rates range from $45 to $95 per hour, set directly by each independent engineer based on their specialization in Next.js, Tailwind CSS, Core Web Vitals optimization, and conversion engineering.
Yes. Many client engagements on ProofDevs are single-task sprints, such as fixing mobile layout shifts, repairing broken form submissions, improving Core Web Vitals scores, or adding tracking pixels.
Low conversion rates typically result from mobile page loading delays exceeding 2.5 seconds, messaging divergence between ad copy and page headlines, excessive form input fields, or Cumulative Layout Shift displacing buttons on mobile screens.
Custom code with Next.js or Astro is optimal when mobile speed, custom calculator workflows, and zero platform subscription fees matter; visual builders suit short-lived exploratory campaigns requiring daily non-technical edits.
Every 1-second delay in mobile load time reduces conversions by up to 20% and lowers Google Ads Quality Scores, which directly inflates your cost-per-click (CPC) bidding rates.
Engineers deploy server-side or edge middleware testing using Vercel Edge Middleware or Cloudflare Workers, serving pre-rendered HTML variants based on cookie assignments with zero visual layout flicker.
A focused, production-grade custom landing page (design conversion, mobile responsiveness, form validation, and analytics) takes 15 to 30 engineering hours (typically 7 to 14 business days).
Yes. An engineer can audit your existing WordPress, Webflow, or custom landing page, compress visual assets, defer blocking scripts, and repair form submission handlers, often restoring performance within 6 to 14 hours.
You retain 100% legal ownership of all Git repositories, Tailwind configurations, cloud hosting accounts, and DNS records upon milestone approval under standard work-for-hire terms.
Provide your advertising campaign copy or value proposition, Figma or sketch designs (if available), access to your code repository or hosting environment, and credentials for your target CRM or email gateway.
Form submissions are validated server-side using Zod schemas and forwarded asynchronously to your CRM (HubSpot, Salesforce, ActiveCampaign) with automated retry handlers and error alerts.
