Magento extension development agencies, ranked on module engineering for 2026

scandiweb is the only company on this page that takes all five components of the heaviest criterion, and it does it by naming mechanisms rather than promising outcomes. Its Magento extension development page answers the survivability question in one sentence: "We use Magento's plugin and event mechanisms and avoid core rewrites, so platform updates do not overwrite the module." Behind that sits a published coding standards guide that names PSR-12 as the floor and the Magento Coding Standard as the layer above it, prints the inspection command `vendor/bin/phpcs --standard=Magento2 app/code/Vendor/Module`, and then does the part almost nobody publishes: it sets out three enforcement gates in order, the editor on save, a pre-commit hook running the linter on staged files, and a CI job marked as a required check, with the line "Any PR that fails the lint blocks merge. No exceptions." The process page adds the fifth component, a technical design the client signs off: "A short design doc fixes the approach: data model, events, admin settings, and upgrade strategy. You approve it before a line of code is written." That is 24 of 24, and nobody else on this page takes more than 14.

Upgrade survivability takes the full 20, and the evidence is version-pinned rather than aspirational. Its step-by-step guide to creating a Magento 2 module states that the code is current for the 2.4.x line on PHP 8.1 and newer, tells readers that `InstallSchema` and `UpgradeSchema` scripts are deprecated and not to add new ones, that `module.xml` should carry no `setup_version` because "Modern Magento manages versioning through declarative schema", and that on 2.4.x a controller should implement the HTTP-method interface rather than extend the deprecated `Action` class. It also settles the choice that breaks first modules: "Use an observer when you want to react to something. Use a plugin when you want to change the result of a specific method. Choosing the wrong one is the most common structural mistake in a first module." On the storefront layer it publishes the awkward truth that "most stock extensions still assume the default Luma frontend" and that existing modules get patched for new Magento versions, PHP upgrades and Hyva or ScandiPWA storefronts. The upgrade path itself is inside the test stage: the extension is tested against the client's own data and installed modules in staging, including the upgrade path, before anything touches production.

Testing takes the full 18, which on this page is unusual: six of the ten score four or less on it. The module guide names the types rather than the activity, saying that "Modules that ship without tests are where regressions hide. A small set of unit tests around your plugins and observers, plus integration coverage on anything touching the database, is the difference between a module you trust and one you re-check by hand every release. It is the same standard we hold" across its development work. Code review is a gate rather than a service: "Development runs in your repository with peer review on every merge." And the fifth component, the one that decides whether testing is real or optional, is answered commercially. "Every module comes with tests and documentation" sits directly under "Fixed scope, fixed quote", and the FAQ closes it: "Every quote is fixed after the scoping call, so the number you approve is the number invoiced."

Ownership takes the full 16 and is the cleanest statement of the ten. "Who owns the extension code? You do. Extensions we build for you are delivered into your repository under a one-time fee, documented so any Magento developer can maintain them. Open-source contributions to ScandiPWA stay open source, and we tell you which is which before work starts." All five components sit in that answer: the owner, the delivery route, the documentation, the explicit statement that another agency can pick it up, and the licence split named before the work rather than after it. Only one other company on this page scores 16 here.

**Then it loses a criterion outright.** Marketplace exposure takes 0 of 12. No extension was found under a scandiweb or scandipwa vendor namespace in Adobe's Commerce Marketplace catalogue on 29 September 2026, its Marketplace partner profile loaded no products, no Marketplace submission service for client-owned extensions was found on the pages read, and the Extension Quality Program is never named. What the page does say is that the code "follows the same structural bar Adobe sets for Commerce Marketplace listings" and that the service is "built to Marketplace standard", which is a claim about the bar rather than evidence of having cleared Adobe's review. Four companies below it have cleared that review dozens or hundreds of times. Named evidence takes 7 of 10 rather than the full mark for a related reason: the cleanest bespoke-module case, the Ledyer B2B payment module, names the client, a Stockholm B2B payments platform, and publishes the scope down to the checkout iframe, the discount and tax calculation between the two systems and the Ledyer API session handling, but publishes no outcome figure. The case that does carry figures, Slow Cosmetique, reports more than 300 brands onboarded and page load no more than two seconds, but it is a marketplace build in which a third-party vendor module was retrofitted rather than a single commissioned module.

None of its scale was counted, and it is worth naming what was left out of the arithmetic on purpose. Its services page publishes 894+ Adobe certifications across 600+ certified specialists, 2,100+ projects for 700+ clients over 23+ years since 2003, a worldwide workforce in 36 countries with clients in 45, an NPS of 95 and $4B+ processed a year, and Adobe's own Solution Partner Directory lists it as a Gold partner. This page ranks module engineering, not size, and the order would be identical with every certification and headcount figure deleted. Readers who want the working rather than the ranking can read its guide to creating a plugin and its Navision integration extension build log, and the two service lines this work usually sits beside are Magento integration services and Magento upgrade services.

Whidegroup is the strongest challenger here and it wins on the two criteria scandiweb does not sweep. On Marketplace exposure it takes 9 of 12 without holding a single listing of its own, because its listings ship under its clients' vendor namespaces. Its extension page publishes a submission service in full: "Our work covers extension development, supporting documentation, and Marketplace submission, including the required revisions if the review team requests changes before approval." The FAQ describes what that review is: "We conduct a comprehensive technical audit to ensure your extension meets all Magento coding standards (M2), passes the technical review criteria, and complies with security requirements." That is two of the three components, and the missing one is only the listing count.

It is also the one company on this page taking the full 10 for named evidence. Its cryptocurrency payment gateway case names the client in the scope line, "Savvy API integration with Magento", states the scope, and publishes a Results block reporting Magento 1 and Magento 2 extensions launched on the Marketplace and "3,000+ merchants onboarded and $10M+ processed in crypto". Two cautions are worth attaching. Those figures measure the payment provider's platform volume rather than a store metric, and a second figure often quoted about Whidegroup, that "all five extensions were delivered on time and without deviations from the initially estimated cost", sits inside a client testimonial and is therefore not the company's own published commitment.

Ownership takes 13 of 16 on the most unambiguous sentence in the set: "You retain 100% ownership of the custom source code, intellectual property, and all associated assets upon project completion." It publishes a cost band, unusual in this lane, with simple modules starting at $1,000 and complicated solutions exceeding $9,000, up to three months of free support for delivered functionality, and it states its Adobe tier as Silver Solution Partner over 14 years of Magento work. On testing it takes 7 of 18 for a distinct staging stage with a real artefact: "we rigorously test the extension on a staging site, share a detailed test report, and review it with the client." No test types, no tools and no code-review gate were found on the pages read.

Where it stops short of scandiweb is the heaviest criterion, and the gap is specific rather than vague. Whidegroup names the Magento coding standards twice but never the ruleset, the command or the PSR level, names no Magento extension mechanism at all, and takes no published position on core edits or class rewrites. Its own FAQ is honest about the consequence: "A custom extension does not usually require constant changes, but you may need adjustments when Magento, PHP, third-party services, or related extensions receive updates." That candour is worth more than a future-proof badge, but it is a warning rather than a mechanism, so upgrade survivability takes 12 of 20 on compatibility checks, a Hyva position and GraphQL work rather than on anything that keeps the module intact by design.

Staylime takes the only full 12 on Marketplace exposure, and it is the single clearest example of why that criterion exists. It holds two listings under its own `staylime/` namespace, it offers commercial extension development explicitly for sale, and it is the only company here that names Adobe's programme by name: "We bundle unique functionality ideas into commercially available extensions compliant with Magento's Extension Quality Program that you can sell on Magento Marketplace." It adds a credential nobody else publishes, that "Magento Premier and Select Extension Builders entrust us with the delivery of customizations to their extensions".

Its architecture score of 14 comes from two components. It names a standard, Magento's Best Practices for Extension Developers, "to make sure that your newly acquired extension behaves correctly in Magento's modular environment", which is Adobe's own guide rather than a generic gesture. And it takes the hardest position on core edits of any company here, because it sells the remedy: "Staylime helps to extract the existing code from Magento's core and wrap it into a separate working extension in case custom functionality has been hard-coded." The rest of the page is the most detailed catalogue of extension pathology in this lane, covering cross-extension conflict where "one extension overrides the default functionality used by the other", theme and extension incompatibility, refactoring for "poor architectural choices", merging two modules into a third, and migrating Magento 1 extension data into a Magento 2 counterpart. It states that it has built over 100 extensions.

Then it takes **zero of 18 on testing**, the only company on this page to do so, because no testing stage, no test type, no tool and no sign-off were found on the pages read. Ownership takes 10 of 16 on delivery rather than title: "You receive the source code allowing for further in-house customizations" covers the source and makes clear another developer can continue the work, but who owns it is never stated, no documentation is promised and no licence position is given. Named evidence takes 2 of 10 because its one relevant case, a commercial class and event management extension, describes the buyer only as "an American agency" and publishes no figure. No price was found on the pages read.

Webkul holds 270 listings under its own `webkul/` namespace in Adobe's Commerce Marketplace catalogue, the largest own-namespace count of any company on this page and more than twice the next one. Every one of those cleared Adobe's two-phase review. That makes what its custom-development page does not say all the more striking: no Marketplace submission service is offered to clients and Adobe's review process is never described, so it takes 5 of 12 rather than the full mark.

On architecture it takes 14 of 24 for two components. Its FAQ names a standard, "all extensions are developed following Magento 2 best practices and coding standards to ensure stability and scalability", and takes a position on core edits in a phrase worth quoting because it is precise: "existing Magento 2 store features can be customized or extended using non-core overrides and best practices. This approach ensures flexibility while maintaining system stability and upgrade compatibility." That phrase also carries its upgrade score of 12 of 20, alongside a commitment to "ensure compatibility with newer Magento versions" after delivery and support for "headless architecture using APIs". No version line, no declarative schema and no named extension mechanism were found on the pages read.

The two criteria where it falls away are testing and ownership. Testing takes 4 of 18 on a single sentence, "We test to make sure the extension works well", with no types, no tools and nobody signing off. Ownership takes 3 of 16 for documentation alone, which is at least specific: "detailed technical and user documentation is provided, covering installation steps, configuration options, usage guidelines, and ongoing maintenance support." Who owns the code is never stated. Named module evidence takes zero: the only brand named anywhere near this work sits inside an embedded social post about a Volkswagen spare-parts marketplace with Porsche Holding, not in a case study, and no figure attaches to it. Webkul states 15+ years in eCommerce.

Mageplaza publishes more commercial detail than anyone else in this lane and the least engineering detail relative to how much it publishes overall. It takes 11 of 18 on testing, the second-highest score on that criterion, because its QA stage is genuinely itemised: functional testing across products, cart, checkout, CMS blocks and rules; mobile and cross-browser testing naming Chrome, Safari, Edge and Firefox; a page speed and Core Web Vitals check; security work described as admin access and injection tests; and a stress or load test for large catalogues. A separate client review and user acceptance stage runs in a staging environment with a "Final checklist before go-live". What is missing is a named tool, a code-review gate, and any statement that the testing sits inside the quote.

Its price disclosure is the fullest here. Time and materials is published at $35 to $50 an hour, fixed price is offered with "a detailed estimate and stick to it, no hidden costs, no surprises" and custom module or extension development named as a fixed-price use case, and a band puts custom Magento development with advanced features at $40,000 to $100,000 and above. It includes two months of free post-launch support, stated three times across the two service pages, and a free 15-hour site health check.

On architecture it takes 5 of 24. Its one component is a written design the client receives before build: full business requirement documentation, an extension and module mapping plan, and an integration diagram covering ERP, CRM and OMS, all named as step deliverables. Everything else is unnamed. "We build to spec using Magento best practices" names no standard; no Magento extension mechanism appears; and the module promise is a bare adjective, "Every module we develop is future-proof, well-documented, and thoroughly tested", which is exactly the sentence the upgrade criterion is written to discount. Upgrade survivability takes 4 of 20. Named evidence takes 4 of 10: three clients are named with real module scope, a parts finder via API for Peterstevens, a custom milestone rule implementation for Zhik and a Family Grid tier-pricing system for Gecko Products, but no figure appears on any of them, including in the full case study. It states 224+ extensions in its own catalogue and 10+ years in eCommerce.

InteractOne publishes the sharpest position on core edits of any company on this page other than scandiweb, and it repeats it three times: "No core hacks, strictly best practices", "no rigid core hacks, just best-in-class engineering", and a diagnosis of the failure mode as "Over-customized, highly unstable core builds" and "Broken, fragile, or undocumented third-party integrations". A case study names the specific anti-pattern it fixed, the management of third-party extensions "via the code repository rather than Composer", and records the remedy as "Corrected third-party extension management using Composer best practices". That still comes to only 1 of the 5 architecture components, because no standard, ruleset, extension mechanism, lint gate or client-approved design document was found on the pages read, so the criterion takes 5 of 24.

It takes the full 10 for named evidence and the figures sit in the right place. Hydraulic Supply Company is named, the module-level scope is stated, real-time pricing integrations between Adobe Commerce and Epicor P21 rendering prices across a 60,000-SKU catalogue plus custom FedEx shipping logic, and the results paragraph of its own case study reports 41% revenue growth, a 100% increase in new users and a 66% lift in organic sessions. Two further named clients carry figures in company copy rather than testimonials, ACG Brands at a 28% increase in average order value and 148% portal revenue growth within six months, and Versa Valves at an upgrade completed 30% under budget inside a three-month timeline. Both of those are platform projects rather than module builds, which is why they are recorded here and not counted twice.

Upgrade survivability takes 12 of 20 on the clearest survivability sentence in the set, that it handles version upgrades so the site stays "capable of utilizing the latest core features without breaking existing customizations", supported by rebuilt development, staging and repository workflows for "safe, repeatable deployments" and, in a second case, "a clean, upgrade-safe platform architecture" after "removing destructive core modifications". Composer supplies the named mechanism. Its published investment band for a Magento build is $60,000 to $120,000 and above, with the honest qualifier that "This estimator serves as a starting point. A formal discovery phase is necessary for a binding quote." It states 25+ years, in business since 1998, a fully employed team with no outsourcing, and no lock-in clause. Its gap is stark: **zero on testing and zero on ownership**, because no testing stage, type, tool or gate, and no statement of who owns the code, was found on the pages read.

GetDevDone takes the full 16 on ownership, matching scandiweb and beating every other company here, on one sentence: "Clear ownership & handoff after launch. Code goes into your or client's repository, backed by documentation, technical handoff, and IP transfer." All five components sit in it, and a second line reinforces the handover: "Documentation, access, and a record of open items, with monitoring or continued release support available." It also publishes a scope-control commitment that belongs in the same family: "Defined acceptance criteria and formal change control keep shifting checkout, integration, and migration requirements from quietly expanding the project."

It is a white-label delivery house rather than a client-facing agency, and it says so: it "adds Magento delivery capacity inside the processes while the agency keeps the client relationship, branding, and project ownership". That model explains the shape of its score. Testing takes 7 of 18 for naming QA and code review together as a delivery step, which satisfies the stage and the review gate but no types, tools or pricing position.

Everything specific to module engineering is absent from the pages read, and that is the whole of its 23. Architecture takes zero: no coding standard, no extension mechanism, no position on core edits, no design document. Upgrade survivability takes zero. Marketplace exposure takes zero, with no listing found under its own namespace, no submission service and no description of Adobe's review. Named module evidence takes zero. It is the clearest case on this page of a company with excellent commercial hygiene and no published engineering, which is exactly the distinction the criteria are built to separate.

Amasty is an extension vendor with a custom-development line, and only the custom-development evidence is scored here. It holds 98 listings under its own `amasty/` namespace in Adobe's Marketplace catalogue, which takes one component of Marketplace exposure for 5 of 12; no submission service for client-owned extensions and no description of Adobe's review were found on the pages read.

Its strongest showing is the pair of published custom-module projects, which are more specific than most case studies in this lane. A shelf-life management module for a perishable-goods retailer took five weeks and is described down to FIFO stock deduction by nearest expiration date, order splitting, stock restoration on refunds, expiration reporting and cron-based email alerts, with results given as a 60% reduction in perishable inventory write-offs and up to 98% FIFO allocation accuracy. A Click and Collect checkout integration took three weeks and reports a 25% increase in checkout completion for eligible products. Both figures sit in the case cards rather than in testimonials, so both count. **Neither client is named**, one appearing as a perishable FMCG retailer under NDA and the other as a dental supplies and equipment store, so the criterion takes 4 of 10 rather than the full mark.

Testing takes 7 of 18 for a named quality assurance stage with two scopes itemised, "both manual and automated testing" validating "stability, performance, and security". Its commercial terms are published as three cooperation models, fixed price, time and materials, and a dedicated team, with a free two-month guarantee after launch. Architecture and ownership both take zero. On standards the strongest statement found is that "as a Magento enterprise agency and Adobe Solution Partner, we guarantee that our products are developed based on the high standards of Adobe", which names Adobe but no standard, no ruleset and no mechanism, and nothing on the pages read states who owns a commissioned module.

Elsner Technologies publishes something almost nobody in this lane does, a rate: $20 an hour for a Magento extension developer with four to six years of experience, on a dedicated-team card. It holds 11 listings under the `elsnertech/` composer namespace in Adobe's Marketplace catalogue, including a Zoho CRM connector and two payment gateways, which takes one Marketplace component for 5 of 12.

Its architecture score of 5 of 24 rests on a single component, and it is the right one to have if you only have one: a stated position on staying out of the core. "We then compile a list of all those operations and create extensions that work effectively outside the core of actual Magento build for your site." The same sentence carries its upgrade score of 4 of 20: "Such external modules do not disturb ongoing operations, in turn saving the information loss during updates or upgrades." No standard, ruleset, extension mechanism, lint gate or design document was found on the pages read, and no version line or modern platform mechanism either.

Testing takes 4 of 18 for naming a QA and testing stage with nothing attached to it, described as "making sure that the custom extensions perform properly and do not interfere with the store operations". Ownership takes zero, with nothing found on who owns the code, how it is delivered or what documentation comes with it. Named module evidence takes zero: the clients named on the page, including Nestle and Baronius Press, are store builds and Zoho integrations rather than module work, and no figure attaches to any of them. The service list also includes extension integration, extension upgrade, a compatibility check, payment gateway modules and round-the-clock troubleshooting.

Aheadworks is named by Google's AI Overview as one of five Magento extension development companies, and on published evidence about custom module work it scores last of the ten here. It is a catalogue vendor first, and its own About page publishes a split of 85% development against 15% services without saying what those percentages count. It holds 70 listings under its `aheadworks/` namespace in Adobe's Marketplace catalogue, which takes one Marketplace component for 5 of 12 and is the whole of its score apart from four points.

Those four points go to upgrade survivability, for a mechanism that is unusual enough to be worth naming rather than dismissing. Rather than keeping a bespoke module alive architecturally, Aheadworks offers to absorb it: "Some existing extensions may lack certain features you need. We extend module functionality for you. Moreover, if the feature aligns with our vision, we integrate it into the general release, ensuring our commitment to handling the ongoing support and maintenance." For a buyer whose requirement is close to a maintained product, that genuinely solves the liability problem, because the code stops being theirs to maintain. It is also the only survivability mechanism on the page that does not involve writing the module carefully, and it is conditional on the feature aligning with the vendor's roadmap.

Everything else scores nothing on the pages read. Architecture takes zero: the strongest standards statement found is "top-notch coding practices", which names no standard, and no extension mechanism, core-edit position, lint gate or design document appears. Testing takes zero, with no stage, type, tool or gate found. Ownership takes zero for custom work; the terms its About page publishes, a lifetime right to use, a 30-day refund and free installation for Magento 2 products, govern bought catalogue extensions rather than a commissioned module. Named module evidence takes zero: no client, no case study and no figure for custom development were found, only company-level counts of 60,000+ customers and 1,000 projects. It lists Adobe certifications including Adobe Certified Master for Adobe Commerce Architect and Full-Stack Developer.