A {shiny} app is a single page: one url, one UI, one server function. That is comfortable while the app stays small. As soon as you want an actual site — a home page, a contact page, one page per user, urls people can bookmark or send by email — you end up faking pages with tabs and conditionalPanel(). {brochure} ...

Diary of a rewrite, episode 2 of 4. Translating your code line by line is the surest way to get it all wrong… In the previous episode we told the story of why we cancelled our own stack decision halfway through, and why we went back to R. If you have not read it, no worries: this one stands on ...

Diary of a rewrite, episode 1 of 4. In February 2026 we chose React to rebuild an internal tool, knowing full well it would take twice as long as doing it in R. It was a deliberate trade: we were not buying an application, we were buying skills. In June, halfway through, with two milestones already delivered, we stopped everything ...

You have thirty minutes before the demo, and your Shiny app still looks like Bootstrap 5 out of the box. We have all been there. The analysis is solid, the model is good, the tables are clean. And then someone from the communication team walks past your screen and says, very politely, that “it doesn’t really look like us”. They ...

After years of powering Shiny applications in production, {golem} — our opinionated framework for building production-grade Shiny apps as R packages — has finally reached a symbolic milestone: version 1.0.0. This is more than a version bump. It marks a mature, stable API, and it’s the right moment to clean up a few legacy behaviors along the way. Here’s what’s ...

Some people have recently been vocal about misuses of the “stratégie du petit r”, a mechanism for sharing data across {shiny} modules that was detailed both in the Engineering Production-Grade Shiny Apps book and in an older post written in 2019 on this blog. And yes, if you’re wondering, I did feel old when I realized this blog post is ...

From prototype to production, make sure nothing breaks… You’ve created a fantastic mockup and your client is delighted. You’re ready to move to production with your application. But one question haunts you: how can you ensure that your application will remain stable and functional through modifications and evolutions? The answer comes down to one word: testing. Three weeks ago, part ...

Deploying a Shiny application to different servers or sharing it with others can be challenging due to differences in R package versions and system requirements. Containerization offers a solution: by packaging your Shiny app and its environment into a Docker container, you ensure it runs consistently anywhere Docker is available. However, not every Shiny developer is familiar with writing Dockerfiles ...

Buckle up, we’re talking about security… While developing the Signature.py application, ThinkR recently faced a security issue – in Python – that deserves our full attention. Versioned on Github, the Signature.py code is analyzed by Dependabot. This is a robot that automatically scans projects for obsolete or vulnerable dependencies and can potentially suggest corrective measures. Dependabot alerted us to a ...

Context Recently, we worked on testing a {shiny} app that relies on values stored within the session$request object. This object is an environment that captures the details of the HTTP exchange between R and the browser. Without diving too deeply into the technicalities (as much as I’d love to 😅), it’s important to understand that session$request contains information provided by ...

Illustration via ChatGPT. There are three hard things in computer science. One is making ChatGPT write “Invalidation” correctly on an image. ​ There’s a saying that goes: “There are only two hard things in computer science: cache invalidation and naming things.” Well, I’d argue there are actually three: 2. Cache Invalidation 1. Naming things 3. Asynchronous Computing   Yes, that’s ...

🏆 We are excited to announce that {signature.py} is the grand winner of the 2024 Shiny Contest in the category ‘Best Shiny Application with Python’! This year, Posit relaunched the Shiny Contest, a competition dedicated to the development of Shiny applications. Participants are asked to create a personal or professional application that addresses a specific problem. The applications are then ...

webR, and the next generation of app with R For the past couple of months, I’ve been sharing how webR will transform the way we build apps with R inside. If you’re unfamiliar, webR is a WebAssembly compilation of R. In simpler terms, it enables R to run within JavaScript environments. If you are familiar, you know it’s a bit ...

Let’s continue our exploration of integrating JavaScript code into a {shiny} application! We will show how to move beyond the classic graphs produced in base R or with {ggplot2} to explore the interactive dataviz production libraries of JavaScript, particularly the Chart.js library. If you missed our first article on integrating JavaScript libraries into a {shiny} application I invite you to ...

You think that some of the components of {shiny} are not very functional or downright austere? Are you looking to implement some feature in your app but it is not available in the {shiny} toolbox? Take a look at JavaScript! JavaScript is a very popular programming language that is often used to add features to web pages. With HTML and ...

But why does downloadHandler now return an empty file!? DownloadHandler context When we start working with {shiny}, we often reach a point where it is necessary to offer the user the option to download a document generated by the application. This document can be a PDF report, a PNG or JPEG image, or anything else. The appropriate function for this ...