JavaScript developers work on problems that belong to no framework: performance and memory issues, legacy codebases still generating revenue, third-party script behaviour, browser platform APIs, and build tooling. Companies hire them because framework expertise does not automatically include profiling skill, event loop understanding, or the ability to modernise code without rewriting it.
A great deal of valuable work sits outside any framework. Pages that stutter on mid-range phones, applications that leak memory over a working day, analytics scripts adding two seconds to load, and codebases from 2016 that still take orders. TechEsperto Solutions provides developers who handle that work.
Our engagements cover performance profiling and remediation, legacy modernisation without rewrites, third-party script and tag work, browser platform API development, build tooling migration, and Node.js scripting and internal tooling. Much of it is diagnostic first, since teams usually know something is wrong without knowing what. Clients scoping broader delivery review our web development services alongside hiring developers directly.
Measurement on real devices and connections, profiling to identify actual causes, then targeted fixes verified against the same measurement. Reported against your field data rather than laboratory scores.
Incremental improvement to older codebases: dependency updates, security patching, module system modernisation, and removal of abandoned libraries. Behaviour preserved throughout.
Auditing what external code costs in load time and main thread blocking, then deferring, replacing, or removing what does not justify itself. Frequently the largest single available improvement.
Workers for off-thread computation, storage strategies, offline behaviour, observers for efficient layout reaction, and media handling. Platform capability used instead of libraries where it fits.
Moving off unmaintained bundlers and configurations onto current tooling, with build times measured before and after. Includes untangling configuration nobody currently understands.
Automation scripts, data processing utilities, and internal command-line tools. Small pieces of work that remove recurring manual effort from engineering teams.
Assessment for this work tests diagnostic ability rather than framework recall. We ask candidates to read a performance profile, explain what a heap snapshot comparison shows, describe how a promise chain schedules against a timer, and identify why a bundle grew. These skills separate developers who can fix an unfamiliar codebase from those who can only extend a familiar one. Application-level engagements are frequently staffed alongside our web application development team.
Reading flame charts, identifying long tasks, attributing main thread time, and distinguishing script execution from layout and paint. The foundational skill for any performance work.
Heap snapshot comparison across a workflow, retained size analysis, and identifying detached nodes and listeners that were never removed. Long-running applications accumulate these steadily.
Understanding execution order across promises, timers, and rendering. Explains a whole category of intermittent bug that otherwise appears to have no cause.
Modern modules, older module formats, and the interoperability problems between them. A persistent source of build failures in codebases that grew across the transition.
Workers, storage options and their limits, intersection and resize observers, abort signals, and streaming. Knowing what the platform provides prevents adding a dependency for something built in.
Reading bundle output to find what added weight, configuring code splitting sensibly, and keeping build configuration comprehensible to the next person who opens it.
Most clients begin with a code review or a performance diagnosis, because the useful next step depends entirely on what is actually wrong. Options then include legacy modernisation projects, third-party script audits, an embedded developer, and a maintenance retainer. Larger programmes are staffed through our dedicated development team model. Transparent pricing, an executed NDA, and full intellectual property transfer apply throughout.
We examine structure, dependency health, known vulnerabilities, build configuration, and obvious performance risks, then report specific issues with fixes ranked by effort against benefit.
Real-device measurement, profiling, and a written explanation of what is slow and why, with fixes prioritised by expected improvement. Delivered whether or not you engage us to implement them.
Dependency updates, security patching, module modernisation, and removal of abandoned libraries on a codebase you intend to keep. Behaviour preserved and verified throughout.
Measurement of what each external script costs in load time, main thread blocking, and requests, with recommendations to defer, replace, or remove. Frequently pays back immediately.
One specialist inside your team handling platform-level work continuously. Suits organisations with an older codebase and a steady stream of changes rather than a single project.
Dependency updates, security patching, performance monitoring against field data, and browser compatibility checking as versions change. Unglamorous and the reason things do not break.
Diagnosis follows a fixed order because guessing is expensive. We measure on devices and connections representative of your actual users rather than on a fast laptop. Profiling identifies causes before anything is changed, since the intuitive culprit is frequently not the real one. Main thread work is separated from network cost, because the fixes differ entirely. Leaks are found by comparing heap snapshots across a repeated workflow. Third-party code is measured specifically, since it is often the largest contributor and the easiest to address. And every fix is verified with the same measurement that identified the problem. Clients working with TechEsperto Solutions get improvements they can see in field data.
Mid-range phones on variable connections behave nothing like development machines. Field data from your actual users is the only measurement that describes the experience you are selling.
The slow thing is frequently not the suspected thing. Hours spent optimising code that accounts for two percent of load time is the most common waste in performance work.
A page can be slow because too much arrives or because too much executes. These need different fixes, and confusing them produces effort in the wrong place.
Repeat a workflow, snapshot before and after, and compare retained objects. Detached elements and forgotten listeners show up clearly and are usually straightforward to fix once identified.
Each external script measured for bytes, blocking time, and requests. Presenting this to whoever owns the marketing tags is frequently more productive than any code change.
Improvement demonstrated against the original method rather than asserted. Field data confirms it a fortnight later, which occasionally reveals that a laboratory improvement did not translate.
Enquiries in this area describe symptoms rather than technologies, which is a useful signal in itself. Slow pages, applications that degrade over a shift, scripts breaking after a vendor update, and codebases nobody will touch are the recurring themes. Our developers work from the symptom to the cause rather than assuming a technology change is the answer. Tag and analytics problems are frequently addressed alongside our data analytics team, since the measurement requirements and the performance cost need reconciling.
Poor responsiveness to interaction, delayed content, and visible layout shifting. Usually a combination of image weight, blocking scripts, and excessive main thread work rather than one cause.
Dashboards and tools left open all day that gradually consume memory until the tab becomes unusable. Almost always listeners, timers, or observers that were never cleaned up.
Vendor updates breaking functionality, tags added without review, and consent tooling interacting badly with everything else. Ownership of this is frequently unclear inside organisations.
Working software with no tests, no documentation, and original authors long gone. Needs someone who will read it carefully and improve it incrementally rather than proposing a rewrite.
Behaviour differing across browsers, older devices, and embedded webviews inside mobile applications. Testing on what your users actually run rather than on current desktop browsers.
Configuration accumulated over years, unmaintained plugins, and builds taking many minutes. Migration to current tooling with build times measured before and after.
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This frequently allows dropping compatibility code for browsers with negligible share, which simplifies the codebase and reduces bundle size.
The entry point is a free code review, or a performance diagnosis where speed is the presenting problem. Give us read access and a description of the symptoms, and we return a written assessment covering dependency health, security exposure, build configuration, structural issues, and measured performance on representative devices, with fixes ranked by effort. Diagnosis is available at a fixed price where you want measurement before committing to remediation. Your team interviews the matched developers, onboarding completes inside a week, and retainers stay optional.
A few days of examination and a written response naming specific issues. Clients regularly act on the findings themselves, which we consider a reasonable outcome.
Field data where available plus testing on devices and connections representative of your users. Establishes the actual baseline rather than the one a fast machine reports.
Profiling and a written explanation of causes at a fixed price, with fixes prioritised. Useful for internal approval, since it converts a vague complaint into a specific work list.
Profiles arrive with relevant platform and diagnostic experience. You assess them against your standards, decline at no cost, and matching continues until the fit is right.
Repository access, environment setup, analytics access for field data, and sprint planning handled immediately so measurable improvement lands inside the first fortnight.
Support begins with dependency updates, security patching, and performance monitoring, which is where the recurring need genuinely sits on older codebases.
Our work and story have been picked up by news outlets and databases worldwide.
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Code reviews are free. Performance diagnosis is a short fixed-price engagement and frequently the best value available, since it prevents effort being spent in the wrong place. Legacy modernisation is quoted in phases. Third-party script audits are a defined short piece of work. Embedded developers are quoted monthly.
Performance diagnosis delivers in under a week. Implementing the priority fixes typically takes two to four weeks. Third-party script audits deliver in days. Legacy modernisation runs in phases of two to four weeks each, sized so each ships independently. Build tooling migration is usually two to three weeks.
Diagnosis and performance work is one senior developer, since it is investigative rather than parallelisable. Legacy modernisation is usually one, occasionally two on very large codebases. Ongoing feature work scales with your roadmap.
Our developers join your repository, board, and chat workspace and follow your review process. Weekly sessions cover measurements before and after, which is a clearer picture of progress than a task list.
Read access for the review, then contributor access if we proceed. Analytics read access helps considerably for performance work. A mutual NDA is signed first. We work in your repository rather than copying code elsewhere.
We staff for at least four hours of daily overlap with your business day across North American, UK, European, and Australian schedules. Reviews, pairing, and release windows sit inside that window.
Dependency updates and security patching, particularly on older codebases where vulnerabilities accumulate quietly. Retainers also cover performance monitoring against field data and compatibility checking as browsers release, which catches regressions before customers do.
Incremental modernisation is right far more often than teams expect, particularly where the application works, generates revenue, and has understood behaviour. It is cheaper, lower risk, and delivers value within weeks. Adopting a framework incrementally suits codebases where new features keep needing complex interactive state, and it can be done page by page without a full rewrite. A full rewrite is justified only when the existing code is genuinely unmaintainable, the requirements have changed fundamentally, or you cannot hire anyone willing to work on it. We assess the codebase and give a direct recommendation, and it is usually the first option.
Tell us what you’re building. Our team will get back to you within one business day with a clear, no-obligation plan.
