Readability — Flesch Measures
Estimate Flesch Reading Ease and Flesch–Kincaid grade level with syllable heuristics.
How it works
- 1Paste or type your text in the input field
- 2Click "Analyze" — processing happens in your browser
- 3Copy the result or download as a text file
What to do next
About Readability Score
Readability Score is built for text processing jobs that fit cleanly into a browser tab. Estimate Flesch Reading Ease and Flesch–Kincaid grade level with syllable heuristics. The processing runs in the page itself, which is why the controls update instantly when you change settings and why a freshly loaded page is ready to do real work the moment it becomes interactive.
Architecturally, Readability Score is a single-page client. The processing layer is standard browser APIs; the UI is a thin React shell on top. Inputs flow through the engine and the output is returned to the browser as a Blob you can save or copy. The 0 MB cap is the only hard limit and it exists to keep memory usage stable on every device.
Readability Score performs the transformation entirely inside the JavaScript runtime. Your file lives in the tab's memory while the engine works on it; the result lives in the tab's memory until the browser triggers the download. Both are released when the tab closes, the way every browser tab releases its memory.
Typical users of Readability Score include students formatting essays, support agents standardising replies and marketers polishing product copy. The thread connecting all of them is the same: a focused text processing task that fits cleanly into a browser tab and benefits from a tool with sensible defaults and minimal setup.
Readability Score works well as a bookmarked utility you reach for when you need it. The first visit shows you what the tool does; the second is when you realise it is a low-friction option for the task and worth keeping in your tab list.
The only practical limit is the 0 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.
Even on its own, Readability Score composes well with the rest of your toolkit. The output is a standard text file that opens in any program that handles the format, so the result of one run can become the input to whatever step you use next.
Some notes on the design of Readability Score. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.
The download is delivered as a clearly named file the moment processing completes — no email link, no "your result will be ready in 5 minutes" queue, no expiry timer. The file is generated in your browser and saved by your browser's normal download flow.
Some context on why Readability Score exists in this form: modern File APIs, high-performance JavaScript engines, and well-maintained open-source libraries now make it possible to perform text processing work entirely in the browser. Readability Score is built on top of that capability, which is why a single page can host the full pipeline.
As a single-page tool, Readability Score stays focused on one text processing step. Multi-step workflows are composed by chaining adjacent tools — each tool produces a standard file the next one can read directly, so a longer pipeline is just a sequence of short tab-and-tab visits.
Pro tip: Readability Score works just as well in a private/incognito window as in a normal one, which is occasionally useful when you want zero browser-history footprint of the job. Another tip: if the tool ever feels slow, it is almost always because the browser tab is competing for CPU with another tab — pausing or closing the heavy ones gives the engine room to work.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
Readability Score is intentionally narrow in scope so the common case is fast and the result is predictable. If you ever need a variation it does not cover, browse the rest of the catalog — there is a good chance an adjacent tool already exists, and switching between tools is just a matter of opening another tab.
How it works
- 1Reach the Readability Score page in your browser to begin.
- 2Add your text input by dropping it onto the page or browsing for it.
- 3Pick any non-default settings you need. Most users leave the defaults alone for the first run and only revisit if the result needs tuning.
- 4Click to start the job. The engine (standard browser APIs) processes the input in the page; you can watch the progress indicator until it completes.
- 5Save the output when it is ready.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Convert a column of names into a comma-separated list for a script using Readability Score.
- Re-case a title from ALL CAPS to Title Case.
- Count the words in a draft to check it fits a brief.
- Find and replace dozens of variants of a phrase in one pass.
- De-duplicate a list of email addresses pulled from a form export.
- Translate plain text into Markdown for a static-site post.
- Strip messy formatting out of copy pasted from a PDF.
- Reformat a JSON blob copied from a log into something readable.
- Generate a slug from a long article title.
FAQ
Perfect syllables?
No — vowel-group counting approximates syllables for English-like text.
Short texts?
Very short samples produce unstable scores; use several paragraphs when possible.
Non-English?
The formulas are English-calibrated; interpret other languages cautiously.
Private?
Yes — local only.
Technical jargon?
Long words raise grade level even when your audience is expert.
Dialog formatting?
Many short sentences lower the grade-level formula differently; review manually.
What should I do if Readability Score fails on my file?
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is in a supported format and that it is below 0 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Can I call Readability Score from a script?
Readability Score is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
Will Readability Score keep working if my Wi-Fi drops mid-task?
Once the page is loaded, Readability Score can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
How accessible is the Readability Score interface?
Readability Score uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
Are there any hidden fees with Readability Score?
Readability Score is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Does Readability Score support batch processing?
Readability Score processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Does Readability Score ask for any browser permissions?
Readability Score only needs the standard web platform — file picker access for the inputs you choose to load, and optionally clipboard access if you copy the result rather than downloading it. There is no microphone, camera, geolocation or background-permission request, because none of those are needed for the work the tool does.
Does Readability Score work on a phone or tablet?
Readability Score runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 0 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.