Is this actually free, or is it a trial?

Free with no time limit. There is no trial period, no watermark, no tag count and no export paywall on any of these. An account adds somewhere central to keep work and AI generation, which needs a provider key that belongs to a person.

Do I need to download or install anything?

No. They all run in the browser. Work is saved in the browser, which means clearing your site data clears it, so export anything you want to keep. There is also a desktop build for sites that will not allow a cloud tool at all.

Two honest ones. Anything using a model needs a provider key you supply, because there is no shared inference key and no metering here. And none of these download to a controller: they design, simulate and document, and putting logic on hardware is a deliberate act with the vendor's own tools. The HMI does export a panel that runs, but as one HTML file for a browser rather than as a vendor panel project.

Can I use this commercially?

Yes. There is no personal-use restriction and no licence that changes when the drawing is for a client.

No account, no download

Free PLC, CAD and SCADA software, in a browser

A ladder editor with a scan-accurate PLC simulator, an HMI and SCADA builder with no tag limit, CAD for panel drawings and schematics, a converter to Structured Text and SCL, and the documents a project is handed over with. No sign-up, no installer, no trial period, nothing that expires.

What "free" usually means in this industry

It is worth being specific, because the word is doing a lot of different jobs. Some tools are free forever and open source. Some are thirty day trials. Some give you a free editor and a runtime that stops after two hours. Some are free up to a tag count chosen to sit just below what a real machine needs. Some are free for personal use and licensed the moment the drawing is for a client.

All of those are legitimate. The problem is finding out which one you have after an evening's work. So here is which one this is, per tool, including what an account adds.

Design and prove it

Write the logic, draw the panel, build the screens, and run them.

Ladder editor and PLC simulator
free PLC programming software, online PLC simulator
Draw ladder logic and run it. The simulator keeps a real output image, holds edge memory per instruction and counts timers in milliseconds rather than scans, so a rung behaves the way it would on a controller rather than the way a teaching tool pretends.
Free
Everything. Twenty three instructions, the tag table, the simulator, export.
An account adds
Saving to a project rather than to this browser, and AI generation.
Open it
HMI and SCADA builder
free SCADA software, free HMI software
Operator screens with eighty seven symbols and alarms following the ISA-18.2 state machine. It binds to the ladder editor's own tag table and runs against the same scan engine, so a start button on the glass starts the motor in the logic. Trends record and export as CSV, and the whole application exports as one HTML file that runs the screen with no install and no network.
Free
The builder, the symbols, the alarms, the runtime, the recording, the panel export, and no tag limit.
An account adds
A project to file it against, and drawing a screen from a description.
Open it
CAD for panels and schematics
free online CAD, free electrical CAD software
Two dimensional drafting for the electrical and panel drawings an automation project produces. Eleven templates numbered the way a control package is read, typed commands, object snap, dimensions, named layers, and panels you can move, resize and put away.
Free
The whole editor, and DXF and SVG export, so nothing is trapped here.
An account adds
Drawings that follow you between machines, filed against a project with its title block filled in.
Open it

Hand it over

Get it out in the formats and documents a project is handed over in.

Ladder to Structured Text and SCL
convert ladder to structured text
Write a ladder program out as IEC 61131-3 Structured Text, Siemens SCL, Rockwell neutral text or PLCopen XML, with a report of what converted cleanly and what did not.
Free
All four outputs and the conversion report. It runs in the browser, so the program does not leave your machine.
An account adds
Nothing. This one is the same either way.
Open it
Automation project document templates
free automation project document templates
The documents a control project is actually handed over with: functional design specifications, I/O schedules, test records, alarm schedules and the rest, as templates you can fill in rather than blank pages.
Free
All seventeen, downloadable without an account.
An account adds
Filling them in against a project, so the tags and the title block come from it.
Open it

Learn it

The reference, the reasoning, and somewhere to ask.

A hundred articles on the things that get asked
PLC programming explained
Around a hundred articles on the questions that come up every week: what a scan cycle actually does, why a timer is not a delay, how analogue scaling goes wrong, what functional safety asks of you, and how alarm rationalisation is supposed to work.
Read it
Somewhere to ask
Questions about a rung that will not latch, a drawing convention, a screen nobody can read at 3 am, or which standard actually applies.
Read it
How the tools work
What each tool does and how to get it to do it, including the parts that are deliberately not obvious.
Read it

Questions

Is this actually free, or is it a trial?: Free with no time limit. There is no trial period, no watermark, no tag count and no export paywall on any of these. An account adds somewhere central to keep work and AI generation, which needs a provider key that belongs to a person.
Do I need to download or install anything?: No. They all run in the browser. Work is saved in the browser, which means clearing your site data clears it, so export anything you want to keep. There is also a desktop build for sites that will not allow a cloud tool at all.
What is the catch?: Two honest ones. Anything using a model needs a provider key you supply, because there is no shared inference key and no metering here. And none of these download to a controller: they design, simulate and document, and putting logic on hardware is a deliberate act with the vendor's own tools. The HMI does export a panel that runs, but as one HTML file for a browser rather than as a vendor panel project.
How does this compare to OpenPLC or CODESYS?: Different jobs. OpenPLC is a real runtime you can put on hardware; CODESYS is a full IEC engineering environment with a free editor and a runtime that stops after two hours. These tools install nothing, expire never, and are for drawing, proving and documenting rather than for running a machine.
Can I use this commercially?: Yes. There is no personal-use restriction and no licence that changes when the drawing is for a client.

And what an account is for

The 5 tools above keep their work in this browser, which means clearing your site data clears it. An account puts them all against one project, so a drawing, a program and a screen are the same job rather than three files, and adds generation from a description, which needs a provider key that belongs to somebody.

Everything, including what needs an account Make one