Your Shopify store and
email list are sitting on
untapped revenue.We engineer both.
High-converting Shopify themes, bulletproof HTML email development, and revenue-driving Klaviyo lifecycle flows—built under one roof with 13+ years of proven execution.
Trusted by brands across eCommerce, SaaS & Retail
Works with the platforms you use
Primary focus on Shopify and Klaviyo. Experience across HubSpot, Mailchimp, ActiveCampaign, Omnisend, WooCommerce, BigCommerce, and 15+ more platforms.
You're not buying “tasks”
You're investing in a unified revenue engine across your Shopify storefront and Klaviyo inbox.
Full Ownership, Zero Headache
No briefing bottlenecks. No micromanaging. We take complete ownership of your Shopify store and Klaviyo channel from strategy to code so you stay focused on scaling.
Fast Wins, Then Scale
We don't wait months to ship. We launch high-impact store improvements and core revenue flows first, track attribution, and compound what converts.
Results or We Walk
We tie every deliverable to measurable conversion and retention lift. No lock-in retainers, no bloated agency overhead, and zero excuses.
Storefront + Inbox Unified
From custom Shopify Liquid sections and speed optimization to 50+ client-tested HTML emails, your storefront and inbox operate as one revenue machine.
More than an agency:
we're your growth team.
Most email agencies don't touch Shopify. Most Shopify devs don't touch email.
We do both: strategy, design, development and automation, under one roof.
Design, Dev & Automation Under One Roof
Unlike most agencies, we handle everything in-house: Shopify builds, pixel-perfect HTML, revenue-driving flows, and full automation setup. No handoffs. No miscommunication. Figma to inbox, start to finish.
13+ Years, 800+ Projects Delivered
We have built and delivered 800+ projects across Shopify builds and every type of email: campaigns, transactional, flows, and full automation series. That depth means fewer mistakes and faster results.
Your Email Looks Perfect. Everywhere.
Gmail, Outlook, Apple Mail, Samsung Mail. Your emails will render flawlessly everywhere. We test across 50+ client and device combinations before every send.
Revenue-First Approach
Every decision we make, from Shopify UX and page speed to subject lines, flow logic, and send timing, is driven by one question: will this make our client more money? Everything we build is designed to make you money.
Stop juggling 3 vendors. We handle it all.
Shopify development, email strategy, design, and automations, all under one roof.
Stop coordinating between your designer, developer, and strategist.
Full-stack Shopify
& email, under one roof.
From Shopify builds to email flows: every layer, fully covered.
Shopify Engineering
Theme Development, Migration, Speed Optimization & Custom Features.
Klaviyo Management
Klaviyo Account Setup, Flow Setup, Account Audit, Sign-Up Forms & SMS Campaigns.
Email Marketing
Email Design, Development, Campaigns, Automations & Deliverability.
From audit to revenue in 4 clear steps.
A battle-tested system refined across 800+ Shopify and Klaviyo projects.
Deep Audit & Revenue Roadmap
We audit your Shopify store speed, conversion bottlenecks, Klaviyo flows, deliverability, and segmentation—giving you a ranked action plan of quick wins.
Design & Flow Architecture
We map out high-converting Shopify OS 2.0 sections and on-brand Figma email designs tailored to every stage of your customer journey.
Bulletproof Build & 50+ Device QA
We hand-code clean Shopify Liquid and responsive HTML emails tested across 50+ email clients—including Outlook, Apple Mail, and Gmail Dark Mode.
Launch, A/B Test & Compound
We launch with zero downtime, monitor real-time attribution, and continuously optimize flows, forms, and store UX to compound your revenue.
Real clients. Real revenue. Real results.
From custom Shopify builds to full-funnel Klaviyo retention architectures—explore our verified growth breakdowns.
From $142K to $1.86M/month for a DTC skincare brand
Rebuilt the Shopify storefront for mobile conversion and deployed a complete 90-day Klaviyo email + SMS retention engine, turning automated flows into a $574K/month channel.
+$438K/month in retention revenue for a luxury DTC brand
Re-engineered an enterprise Shopify store and replaced blanket promo blasts with an 8-stage Klaviyo retention system, scaling store revenue from $2.18M to $5.12M/mo.
$84,320 in 7 days for a DTC apparel brand
Executed a synchronized 7-day Klaviyo email and SMS flash campaign with automatic buyer suppression and custom Shopify cart tier unlocks.
Crafted to look flawless and convert.
A look at our custom Shopify theme builds, Klaviyo flow systems, and hand-coded HTML email templates.
Full Portfolio →
58% Open Rate · 4.8× ROIMulti-Step Welcome Series
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+24% Conversion · 1.4s LoadCustom Shopify OS 2.0 Rebuild
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50+ Clients & Dark Mode QAFigma-to-HTML Campaign System
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+$142K Recovered RevenueHigh-Recovery Cart & Checkout Flow
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100% Render AccuracyBulletproof Outlook & Mobile HTML
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−31% Cart AbandonmentCore Web Vitals & Speed Overhaul
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11.4% Opt-In ConversionZero-Party Data Capture Pop-Ups
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$84.3K in 7 DaysVIP Email + SMS Flash Launch
Explore Service →
Built by a Shopify & email obsessive.
PlusSquire is led by Zahidul Islam—a senior Klaviyo strategist, bulletproof HTML email developer (13+ years), and Shopify theme engineer (2+ years) who has personally shipped 800+ projects and 7,000+ custom email templates for global eCommerce brands.
Unlike traditional agencies that pass your account to junior coordinators, you work directly with a battle-tested technical team that bridges custom Shopify Liquid engineering and high-converting Klaviyo retention systems.
- ✓13+ Years Klaviyo, Email Design & Bulletproof HTML Email Development
- ✓2+ Years Custom Shopify OS 2.0 Liquid Theme Development & Speed Tuning
- ✓Top Rated Plus on Upwork (Top 3% Talent · 100% Job Success · 800+ Projects)
- ✓Pixel-perfect Figma/PSD to Klaviyo HTML tested on 50+ email clients & Dark Mode
- ✓Trusted by DTC brands & white-label eCommerce agencies across US, UK, CA & AU
Why PlusSquire over everyone else?
Most agencies look the same on paper. Here's what actually separates us.
✓ Good Fit
- ✓Established brand ready to scale revenue across their store and inbox
- ✓Values long-term partnership over cheap one-off work
- ✓Wants a team that thinks, not just executes
- ✓Open to honest strategy conversations
- ✓Focused on business growth, not just vanity metrics
✗ Not a Fit
- ✗Looking for the cheapest option available
- ✗Needs results overnight with no strategy budget
- ✗Wants someone who just says yes to everything
- ✗Not ready to invest in their store and inbox as revenue channels
- ✗Prefers to micromanage every single deliverable
What our clients
actually say.
Backed by 800+ completed projects and a 100% Job Success Score on Upwork.
“Zahidul is one of the best Shopify and email professionals I've worked with. He handles design, development, and Klaviyo flows end-to-end, delivering polished, production-ready work every time. We've worked together for 5+ years now.”
“Our Klaviyo flows went from generating 10% of revenue to over 35% in 3 months. Zahidul knew exactly what to build and why. Highly recommend for any eCommerce brand serious about email.”
“Rebuilt our entire Shopify store from scratch, pixel-perfect and blazing fast. Conversion rate jumped noticeably within the first month, and the handoff was completely smooth.”
“Exceptional HTML email developer. Provided Figma to HTML email development with templates that worked perfectly in Outlook, which is notoriously difficult. Fast, professional, and gets it right the first time.”
“Set up our entire Klaviyo account from scratch. Every flow, segment, and integration was done perfectly. Our abandoned cart recovery alone paid back the entire project cost in the first week.”
“Handled both our Shopify migration and Klaviyo setup end-to-end, one team, zero handoffs, and it just worked from day one. Exactly the kind of full-stack partner we were looking for.”
“Our store loads in under 2 seconds now. Cart abandonment dropped and mobile conversions are up significantly since the Shopify rebuild.”
“Zahidul is one of the best Shopify and email professionals I've worked with. He handles design, development, and Klaviyo flows end-to-end, delivering polished, production-ready work every time. We've worked together for 5+ years now.”
“Our Klaviyo flows went from generating 10% of revenue to over 35% in 3 months. Zahidul knew exactly what to build and why. Highly recommend for any eCommerce brand serious about email.”
“Rebuilt our entire Shopify store from scratch, pixel-perfect and blazing fast. Conversion rate jumped noticeably within the first month, and the handoff was completely smooth.”
“Exceptional HTML email developer. Provided Figma to HTML email development with templates that worked perfectly in Outlook, which is notoriously difficult. Fast, professional, and gets it right the first time.”
“Set up our entire Klaviyo account from scratch. Every flow, segment, and integration was done perfectly. Our abandoned cart recovery alone paid back the entire project cost in the first week.”
“Handled both our Shopify migration and Klaviyo setup end-to-end, one team, zero handoffs, and it just worked from day one. Exactly the kind of full-stack partner we were looking for.”
“Our store loads in under 2 seconds now. Cart abandonment dropped and mobile conversions are up significantly since the Shopify rebuild.”
“Zahidul is one of the best Shopify and email professionals I've worked with. He handles design, development, and Klaviyo flows end-to-end, delivering polished, production-ready work every time. We've worked together for 5+ years now.”
“Our Klaviyo flows went from generating 10% of revenue to over 35% in 3 months. Zahidul knew exactly what to build and why. Highly recommend for any eCommerce brand serious about email.”
“Rebuilt our entire Shopify store from scratch, pixel-perfect and blazing fast. Conversion rate jumped noticeably within the first month, and the handoff was completely smooth.”
“Exceptional HTML email developer. Provided Figma to HTML email development with templates that worked perfectly in Outlook, which is notoriously difficult. Fast, professional, and gets it right the first time.”
“Set up our entire Klaviyo account from scratch. Every flow, segment, and integration was done perfectly. Our abandoned cart recovery alone paid back the entire project cost in the first week.”
“Handled both our Shopify migration and Klaviyo setup end-to-end, one team, zero handoffs, and it just worked from day one. Exactly the kind of full-stack partner we were looking for.”
“Our store loads in under 2 seconds now. Cart abandonment dropped and mobile conversions are up significantly since the Shopify rebuild.”
Common questions, straight answers.
Everything you need to know about working with PlusSquire.
Most email agencies cannot touch Shopify Liquid code, and most Shopify developers do not build Klaviyo flows or hand-code Outlook-proof HTML emails. At PlusSquire, we engineer both under one roof—meaning zero vendor handoffs, faster launches, and a storefront + inbox built as one revenue system.
Yes! We regularly partner with Klaviyo Elite, Shopify Plus, and creative agencies across the US, UK, Canada, and Australia. Whether you need Figma-to-HTML email coding, complex Klaviyo flow builds, or custom Shopify OS 2.0 sections, we plug seamlessly into your Slack and project management tools.
Custom HTML email templates and single flow builds are typically delivered within 24–72 hours. Full Klaviyo account setups take 7–10 days, and complete custom Shopify theme builds or migrations take 3–6 weeks.
Guaranteed. With 13+ years and 7,000+ HTML templates coded, we test every email across 50+ device and inbox combinations (including legacy desktop Outlook and iOS/Android Dark Mode) before launch.
Never. We offer both fixed-price one-time projects (audits, theme builds, flow setups, template coding) and flexible monthly retainers that you can pause or cancel anytime.
Ready to turn your store and inbox
into your #1 revenue channel?
Let's build something
great together.
Whether it's a custom Shopify build, a Klaviyo retention overhaul, or white-label agency support—tell us about your goals. We respond within 24 hours.
hello@plussquire.com📅 Prefer to talk first?
Book a free 30-minute discovery call, no commitment, just a quick chat to see if we're a good fit.