Most free file tools on the web work the same way: the visitor uploads a file, a server processes it, and the result comes back. It is the easy architecture, and it means ID cards, contracts and payslips pass through someone else’s computer. Reembun, a tools platform we built and run ourselves, takes the opposite position: no file ever leaves the visitor’s device.
This case study walks through the technical decisions behind it, the problems that were genuinely hard, and what it says about the work we take on as a delivery partner for agencies.
The brief we set ourselves
- Server-class work without a server. Compressing PDFs, converting video, decoding iPhone HEIC photos and recognising text in 102 languages, all inside the browser, on mid-range phones as well as laptops.
- Two languages as two real markets. English and Indonesian, with fully translated URLs and reciprocal hreflang, not a translated page at an English address.
- Reliability that is measured, not assumed. A file tool that looks fine but silently refuses files is the worst failure a tools site can have, and it had to be caught automatically.
- Open source licence compliance by design. The processing engines are open source components, and every licence had to be honoured and attributed properly from the first release.
The architecture
| Decision | Why |
|---|---|
| Static site with interactive islands that load only when used | Pages open fast, and heavy tool code is not downloaded until a visitor actually uses the tool |
| WebAssembly processing engines in the browser | Server-grade work runs on the visitor’s device, so nothing is transmitted |
| Translated URLs and per-page hreflang for Indonesian | A clean language signal for search engines and readers alike |
| Installable web app with offline support | Tools a visitor has used keep working with no connection |
| Automated hit-testing of every file tool at eight viewport sizes | Failures invisible to the eye are caught before they ship |
Related reading: Offshore Development Partner in Indonesia: A Guide for Global Agencies
What was genuinely hard
Making heavy work feel light
The engines for PDF rendering, video conversion and text recognition are several megabytes each. Loading them on every page would have wrecked page speed, so each loads only when a visitor commits to using a tool, and is then cached so it never downloads twice.
Hitting a number, not a level
People compressing a PDF usually have a limit from an upload form, not a preference. We built a mode that takes the limit, tries a lossless rebuild first, and only then redraws pages at the sharpest resolution and quality that fit. In our tests, a two page 1.81 MB scan came in at 158 KB against a 200 KB limit, with a quality floor that keeps small print readable.
Catching the failures nobody reports
A drop zone that stops accepting files looks completely normal, and visitors simply leave. We now run automated browser checks across eight viewport sizes for every file tool, alongside hundreds of unit assertions for the tax and finance calculators.
Related reading: How Agencies Add Delivery Capacity Without Adding Headcount
Results we can point to
- Hundreds of tool pages across two languages, including Indonesian tax calculators that show the regulation behind every rate.
- Text recognition in 102 languages, entirely on the device.
- A privacy claim anyone can verify: open the browser’s Network tab while using any tool and no request carries the file. Try it on the PDF compressor.
Why this matters to an agency choosing a partner
Reembun is our own product, so we carry the consequences of every decision on it. The same habits go into client work: architecture chosen for the actual constraint rather than the easy default, performance treated as a feature, automated testing for the failures that are expensive precisely because they are silent, and licensing handled before it becomes a problem.
Frequently Asked Questions
Can client-side processing work for business applications?
For a lot of work, yes. Document processing, text extraction, file validation and heavy calculation can all run in the browser. Shared storage, approvals and integrations with other systems still need a server, and the right design usually combines both.
Is browser-based processing fast enough?
For everyday work it is often faster, because there is no upload or download. Very heavy jobs, such as re-encoding long 4K video, remain faster on a server or a powerful desktop.
Do you build this kind of thing under an agency’s brand?
Yes. We work as a white label delivery partner, under your brand and never in contact with your client, for custom web applications as well as WordPress and SEO work.
About RHP
PT RHP Cipta Digital is an international digital and marketing agency based in Jakarta. We work as a white label delivery partner for agencies abroad, covering custom web and application development, WordPress development, and SEO.
We have delivered more than 100 projects and generated over 1,000 B2B leads for clients in the United States, Indonesia, and several other countries.
Talk to us about your next build
If you have a project where privacy, performance or reliability is the hard part, we are happy to talk through how we would approach it, including the parts that would not suit us. The first conversation is free and carries no obligation.
