Simmodlr — now live

Understand your system
before you commit to it.

Simmodlr is a set of modelling components. The first released component is a browser-based discrete-event simulation tool. Model queues, resources, and service processes — no install, no code, results you can rely on.

Start modelling → See a worked example

No install · Runs entirely in your browser · simmodlr.app

The problem

Spreadsheets lie about queues.

Queueing formulas assume steady-state averages. Real systems don't work that way — and the gap between the formula and reality grows fast as utilisation rises.

⚡

Variability is non-linear

A server at 90% utilisation has roughly nine times more wait time than one at 50% — not 80% more. The formula gives you the wrong number by a wide margin.
📊

Distributions are not averages

Exponential service times and empirical service times produce different queue dynamics. Point estimates hide variance. Confidence intervals reveal it.
🔗

Multi-stage systems compound

When stages share resources, blocking and starvation emerge that no formula predicts. Simulation models these interactions event by event.

Mean wait time — formula vs simulation (single server)

3.5m

50%

6.5m

65%

13m

80%

18m

41m

90%

36m

190m

95%

Formula

Simulation

Open workflow

Built-in help. Your own tools.

Simmodlr can help you build models, analyse results, and test improvements. Prefer your own AI tools? Use them too.

✏️

Build with Simmodlr

Create a model from a plain-English description, then inspect and edit it.

📊

Analyse with Simmodlr

Explore results, identify pressure points, and generate recommendations.

🔓

Use your own AI tools

Use your preferred chat tools to build a model and get a different perspective on the results and options.

Capabilities

Design. Run. Analyse. Change.

Build the model, watch it run, understand the results, then test the change — all in one browser workflow.

✏️

Design — three ways to build your model

Describe the system in plain English, then review and adjust the model on the canvas or in the editors.

Describe

Describe your process in plain English
Simmodlr builds the first version
Review and adjust before anything runs

Draw

Drag-and-drop layout
Stays in sync with the editors
Easy visual checking

Form Based

Robust, Validated, Easy to Use
Definition of Entities, Events and Queues

▶️

Run — robust experiments

Watch queues form, resources become busy, and entities move through the process.

Live flow on the canvas
Queues, completions and utilisation
Visible behaviour before conclusions

📊

Analyse — confidence in the results

Explore builds confidence in the results and highlights what needs attention.

Confidence target checking
Plain-English explanation
Pressure points highlighted

🔁

Change — test improvements safely

Test a proposed change, compare the result, then save what works.

Temporary model changes
Before-and-after comparison
Save only what works

Worked example

A&E triage, from prompt to tested change in minutes.

A plain-English brief becomes a working emergency-department model: arrivals, triage, queues, doctors, and exits.

Then Simmodlr runs it, analyses the results, recommends a doctor-capacity change, and tests it before anything is saved.

✏️DesignDescribe the system and review the proposed model

▶️RunExecute the pathway and watch the model behave

📊AnalyseBuild confidence and understand the pressure points

🔁ChangeTest the improvement before saving it to the model

01 — Design

Simmodlr drafts the model from the brief

Model proposal describing emergency department triage with arrivals, triage queue, doctor priority queue, resources, and exits

Review the proposed flow before saving it to the model library.

02 — Run

Watch the process in action

Running model canvas showing patient arrivals, triage queue, doctor queue, exit, doctor consultation complete, utilisation, throughput, and waiting counts

Seeing the model run makes the process visible: queues, movement, resource use, and flow.

03 — Analyse

Explore provides confidence in the results

Explore results summary showing confidence achieved with 45 replications, average wait, time in system, arrivals, served patients, and no early leavers

Explore builds confidence, summarises the results, and recommends what to change next.

04 — Change

Test the proposed change safely

Analyse and compare panel showing doctor bottleneck, proposed doctor capacity change from 3 to 4, and before-after performance metrics

Test the recommendation, compare the result, and save it when it works.

Large Simmodlr model organised into coloured sections with many connected queues, activities, resources, routes, and handoffs

Simple to start. Built for real systems.

The triage example is easy to follow, but the same canvas can hold larger pathways too. Sections help organise complex models with branching routes, shared resources, priorities, and handoffs across a whole service.

Who it's for

If you have a problem to solve, this is for you.

You do not need a background in simulation. If you have a real problem and need an honest answer, this is for you.

"We need to understand this before we spend the money."

A decision is coming — a new service, a change in staffing, an investment in capacity. You need numbers you can defend, not a back-of-envelope estimate. Simmodlr gives you a model you can run, tweak, and present — built in hours, not weeks.

→ Run the scenarios. Know the risks before you commit.

"The system is struggling and I need to know why."

Queues are building. Waits are longer than they should be. Something isn't working but it's not obvious where the problem actually is. Simulation lets you see inside the system — test changes safely before touching anything real.

→ Find the bottleneck. Test the fix. Then act.

"I want to learn simulation properly, without the cost."

You're studying operations, engineering, or healthcare systems — or teaching it. Commercial simulation tools are expensive and slow to learn. Simmodlr has a generous free tier, runs in a browser, and doesn't hide how it works.

→ Free tier. No install. No licence barrier. No black box.

Understand your systembefore you commit to it.