ADVANCED TEXT & CONTENT
Free Sentence Complexity online
Flesch readability and grade level.
Sentence Complexity is a free browser tool that lets you flesch readability and grade level. Enter your file, review the live Sentence Complexity output, then copy or download it. Sentence Complexity works on your device only, so no file or text is ever uploaded.
- Free to use
- No signup
- Private and local
- Unlimited use
Why use Sentence Complexity
- flesch readability and grade level without installing software
- Your file is processed on your device by Sentence Complexity, never uploaded
- Sentence Complexity needs no account, email address or payment details
- Sentence Complexity shows live output that updates as you type
- Sentence Complexity is keyboard accessible and screen-reader friendly
- Sentence Complexity is free forever, with no watermark on the result
Sentence Complexity runs entirely inside your browser. Your file is never uploaded, stored or shared, and nothing is retained once you close the tab.
How to use Sentence Complexity
- Enter your file Paste or type your file into the input panel above.
- Adjust the options Set the options that control how Sentence Complexity handles your input.
- Run the tool Sentence Complexity works instantly on your device, with no queue and no upload wait.
- Copy or download Copy the output to your clipboard or download it as a file, free and unlimited.
Benefits
Private by design
Your file stays on your device while Sentence Complexity works. Sentence Complexity never sends it to a server, so confidential work stays confidential.
Instant results
There is no upload step, so Sentence Complexity starts the moment you add your file.
No signup, no limits
Use Sentence Complexity as many times as you want. Sentence Complexity asks for no account, adds no watermark and keeps no paid tier gating the output.
Works on any device
Sentence Complexity runs in any modern browser on desktop, tablet and phone, with a keyboard-accessible interface throughout.
Who it is for
For marketers
Marketers use Sentence Complexity to publish campaign assets without installing software: flesch readability and grade level on a shared or locked-down machine.
For students
Sentence Complexity helps students hand in coursework quickly, since your file never leaves the laptop it was created on.
For freelancers
Sentence Complexity helps freelancers send client deliverables quickly, since your file never leaves the laptop it was created on.
How it works
Sentence Complexity loads your file into memory, applies the change you requested to the underlying data rather than to a screenshot of it, and writes a fresh copy for download. Your original stays untouched on disk, and every step of Sentence Complexity happens inside your browser sandbox.
Frequently asked questions
Is Sentence Complexity free to use?
Yes. Sentence Complexity is completely free with no account, no trial and no usage cap. Every feature on this page is available on the first visit.
Does Sentence Complexity upload your file to a server?
No. Sentence Complexity processes your file inside your browser, so it never reaches a DocTools server. That also means the tool keeps working if your connection drops mid-task.
Is there a limit on how much input I can use?
Sentence Complexity handles inputs into the megabytes without trouble; the only real limit is how much your browser tab can hold in memory.
Do I need to install anything to use Sentence Complexity?
No installation is needed. Sentence Complexity runs in Chrome, Edge, Firefox and Safari, on desktop and on mobile, with no extension or plugin.
Can I use Sentence Complexity on a phone or tablet?
Yes. The Sentence Complexity interface adapts to small screens and supports touch input, though very large jobs are faster on a desktop browser.
What happens to your file when I close the tab?
It is discarded. Sentence Complexity keeps everything in temporary browser memory, so closing the tab removes every trace of the session.
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Last updated: 2026-09-07