Tachi is a free speed-reading trainer for the browser. The answers below separate what is well established from what is marketing, and describe exactly what the web app does.
Speed reading basics
Speed reading is a loose label for techniques that aim to raise reading rate above a person's normal pace, usually measured in words per minute (WPM).
The techniques fall into three families: changing how text is presented (for example RSVP, where words appear one at a time), changing habits (fewer regressions, using a pacer, reading in phrases), and reading selectively (skimming and scanning).
They are not equally well supported. Selective reading reliably saves time when the gist is enough; claims of reading several times faster with full comprehension are not supported by research.
Adults reading English silently average about 238 words per minute for non-fiction and about 260 words per minute for fiction.
These figures come from Brysbaert (2019), a meta-analysis of 190 studies with 18,573 participants. The same analysis puts reading aloud at about 183 words per minute.
Individual speed varies with the difficulty of the text, vocabulary, familiarity with the topic and the reason for reading, so one person's rate moves around during the day.
RSVP stands for rapid serial visual presentation: text is shown one word or one short group of words at a time at a fixed spot, at a set pace, so the eyes do not have to move along lines.
RSVP began as a laboratory method for studying reading and attention and later became the basis of many speed-reading apps.
Tachi's reader is an RSVP reader. You choose the pace (100–1000 WPM) and how many words appear at once (1–7), and you can pause, step back or scrub to any position.
Subvocalization is the inner speech most people hear while reading silently. You do not need to eliminate it, and trying to can hurt understanding.
Speed-reading courses often describe the inner voice as a bad habit. The research review by Rayner et al. (2016) concludes instead that inner speech supports comprehension and that suppressing it tends to make understanding worse.
A more realistic aim is to stop the voice from dragging on easy material, for example by reading in phrases, while letting it work on anything dense.
A Schulte table is a square grid of shuffled numbers, classically 5×5 with the numbers 1 to 25, in which you find the numbers in ascending order as fast as you can.
It originated as a psychological test of attention and visual search and is named after the German psychiatrist Walter Schulte. Speed-reading programmes adopted it as a peripheral-awareness exercise: the usual instruction is to keep your gaze on the centre cell and find each number without moving your eyes.
Tachi's Schulte Table drill offers 3×3, 4×4 and 5×5 grids, times each run, counts wrong taps and keeps your best time per grid size.
A tachistoscope is a device that shows an image, word or number for a precisely controlled fraction of a second. Psychologists have used it since the nineteenth century to study perception, and it later became a tool for recognition and reading training.
The name comes from Greek words meaning "swiftest" and "to view".
In Tachi's Tachistoscope drill a word of 3 to 6 letters flashes for between 200 and 5 milliseconds, depending on the level, and you type what you saw. Ten words make a round. On a screen, the shortest real exposure is limited by the display's refresh rate.
Bionic reading is a text style that bolds the first letters of each word to give the eye an anchor. Controlled testing has not found that it makes people read faster.
Snell (2024) had participants read 100 paragraphs in either bionic or normal formatting and found no significant difference in reading times.
Tachi includes a Bionic mode in its reader because some people simply like how it looks. Treat it as a preference, not as a speed technique.
Does it work?
Only partly. You can get through text faster, but beyond your normal pace speed is generally paid for with comprehension; no method has been shown to double or triple reading speed while keeping full understanding.
That is the central conclusion of Rayner et al. (2016), a review of decades of reading research. Skilled readers already read quickly, and the main limit is how fast the mind recognises words and builds meaning, not how fast the eyes move.
What does help: skimming when a rough understanding is enough, knowing the subject and its vocabulary, and simply reading a lot. A trainer like Tachi is best used for deliberate, paced practice and for getting through material where a moderate level of comprehension is acceptable.
At moderate speeds and on easy text, RSVP comprehension can be fine. At high speeds and on difficult text it tends to drop, mainly because you cannot glance back at something you misread.
Rayner et al. (2016) note that eye movements take up no more than about a tenth of reading time, so removing them saves little, while losing the ability to re-read removes a tool readers rely on.
Tachi's reader is built with that trade-off in mind: it lengthens the display time at punctuation, lets you pause and step back a chunk, and offers two full-text modes (Highlight and Pacer) that keep the surrounding sentences visible.
There is no strong evidence that they do. People clearly get faster at the drills themselves, but good studies showing that this carries over to reading speed on ordinary text are lacking.
Reading speed is limited mostly by language processing rather than by eye muscles or the width of the visual field, which is why researchers are sceptical of eye-training claims.
Tachi's drills are short attention, visual-search and word-recognition exercises. They are a reasonable warm-up and a way to practise focus; the reader, where you practise on real text, is where reading practice happens.
Reading more, building vocabulary and background knowledge, and matching your speed to your purpose. These are the factors research ties most closely to fast, accurate reading.
Rayner et al. (2016) conclude that language skill is at the heart of reading speed, and that practice at reading for comprehension is what improves it.
Practical habits that follow from this: decide before you start whether you need the details or just the gist, skim structure first on long documents, and slow down on purpose where the text is dense.
About ten minutes a day is a sensible routine in Tachi: a few one-minute drills followed by five minutes of paced reading. This is a practical suggestion, not a research-backed dose.
Each drill is designed to take roughly thirty seconds to two minutes. In the reader, start at a pace where you understand nearly everything and raise it one step at a time only while that stays true.
A full ten-minute plan is laid out on the "How Tachi works" page at https://tachiapp.com/how-it-works.
Using Tachi
Tachi is a free speed-reading trainer that runs in the browser at tachiapp.com. It combines 9 short eye and perception drills with an RSVP reader for your own texts.
The drills are grouped by purpose: warming up, widening your span and sharpening recognition. The reader plays pasted text or imported PDF, EPUB and text files at a pace you set.
Tachi is built and run by an independent solo developer. It needs no account and keeps your data in your browser.
Yes. The Tachi web app is free, with no paywall, no daily limit, no account and no advertising.
An iOS app is planned but not yet released. According to Tachi's support page, subscriptions will exist only in the iOS app and will be billed by Apple; the web app stays free.
No account is needed, and nothing syncs. Your library, settings and progress are stored in the browser you use.
Because Tachi has no accounts and no server holding user data, each browser and device keeps its own copy. Clearing the site's data in your browser removes it.
Tachi has 9 drills in three groups: warm-up (13-Point Eye Workout, Circular Eye Motion, Hourglass Focus), span (Schulte Table, Peripheral Letters) and recognition (Tachistoscope, Word Search, Similar Words, Text Scan).
The warm-up drills are timed gaze-following exercises of 30, 60 or 120 seconds. The span drills ask you to find or identify items away from the point you are looking at. The recognition drills ask you to identify, match or locate words quickly.
Each drill is explained step by step at https://tachiapp.com/how-it-works.
The reader has 6 modes: Flash, Bionic, Fade and Wide show one chunk at a time, while Highlight and Pacer move through the full text.
Flash shows one chunk at a fixed point and, for single words, colours the letter at the optimal recognition point. Bionic bolds the start of each word. Fade adds a faint preview of the previous and next chunk. Wide places the chunk between two guide dots. Highlight scrolls the whole passage and lights up the current chunk. Pacer does the same but dims the text ahead and underlines the current chunk.
The reader runs from 100 to 1000 words per minute in steps of 25, starting at 300, and shows 1 to 7 words at a time.
Other settings are smart chunking (groups words by length so long words are not crowded), a pause on punctuation, an audio metronome that clicks on each chunk, font size, 7 fonts and 9 reader themes.
On a keyboard, Space pauses, the left and right arrows step one chunk, the up and down arrows change speed and Escape closes the reader. Tachi remembers where you stopped in each text.
PDF, EPUB and plain-text files (TXT and Markdown). You can also paste text from the clipboard.
Files are converted to text inside your browser and are never uploaded. PDFs need a text layer: scanned, image-only or encrypted PDFs cannot be imported. Images, tables and page layout are not kept, because the reader works on plain text.
Texts are saved in the browser's local storage, which has a size limit, so a very large book may not fit.
Yes. The reader includes OpenDyslexic, Atkinson Hyperlegible and Lexend, alongside Inter, a serif, a monospace and the system font.
Font size, reader theme and reading mode can be changed independently, so you can combine a font with, for example, the sepia theme. Tachi is not a medical or assistive product and makes no claim that a particular font improves reading; pick what is most comfortable for you.
The interface, practice passages and drill word lists are available in 29 languages, including right-to-left languages.
The languages are: English, 简体中文, हिन्दी, Español, العربية, Français, বাংলা, Português, Русский, اردو, Bahasa Indonesia, Deutsch, 日本語, Türkçe, 한국어, Tiếng Việt, Italiano, فارسی, ไทย, Polski, Українська, Bahasa Melayu, Nederlands, Română, Ελληνικά, Čeština, Magyar, Svenska, עברית.
You can read your own text in any language. For scripts written without spaces between words, such as Chinese, Japanese and Thai, the reader splits text into words using the browser's built-in word segmenter.
Yes. Texts you paste or import, your settings and your progress stay in your browser's local storage and are not sent to Tachi.
Tachi has no accounts, no advertising and no analytics or tracking scripts. As with any website, the hosting server processes standard request data such as IP address and browser type in order to deliver the pages.
To delete everything, choose "Reset all data" in the web app's Settings or clear the site's data in your browser. This erases your library, reading positions, history and settings in that browser; nothing is stored on a server.
The full policy is at https://tachiapp.com/privacy.
The web app needs an internet connection to load. It is not an offline app.
Once loaded, your texts are processed in the browser rather than on a server, which is why they are never uploaded.
Not yet. An iPhone app is announced as coming soon to the App Store but has not been released, and no Android app has been announced.
The web app works in mobile and desktop browsers in the meantime.
Tachi is made by an independent solo developer. For help, bug reports or feature requests, email support@tachiapp.com.
You can also send feedback from Settings inside the web app, which opens a message in your own email program.