A betting browser extension is an add-on for Chrome or a similar browser that works inside the bookmaker pages you open. It can read what a page shows and act on it, most often by putting a selection into your bet slip, and the permissions you grant when you add it decide how far that reach goes.
The useful kind saves you finding a runner or a market on a bookmaker's site and leaves the stake and the Place button with you. The risky kind can see far more than it needs, or places the bet itself, which is where an extension stops being a helper and becomes a bot. Of all the betting tools in Australia, it is the one that sits closest to your logged-in accounts.
What a betting extension does on a bookmaker page
An extension can do four kinds of job on a page it has access to, and the last is the one that changes what you are installing.
| Job | What it touches | Who places the bet |
|---|---|---|
| Opens the right event or race | The tab's address | You |
| Adds a selection to the bet slip | The page's own buttons | You, at the Place button |
| Reads the page: an odds overlay showing other bookmakers' prices, or a bet tracker copying your bets and balance | What the page shows, your bet history included | Nobody: nothing is placed |
| Types a stake and clicks Place | The whole slip | The extension |
Slip filling works like this: you choose a selection somewhere else, such as on an odds board, and the extension carries it to the bookmaker's page so you do not have to search for it. Reading a page is the job of odds overlays, which show other bookmakers' prices beside the one you are on, and bet trackers, which copy your bets and balance into a dashboard; a tracker needs access to your account pages to do it. Placing the bet is full automation running in your browser.
What extension permissions let it see
When you add an extension from the Chrome Web Store, Chrome first shows the permission warnings it carries: plain statements of what it will be able to do. The wording changes between browser versions, but the meaning of the main warnings does not. An extension loaded unpacked, from a downloaded folder, shows no warnings at all (checked October 2026), so open its details on the extensions page and read its permissions and site access before you use it.
| The warning, in substance | What it allows | On a betting site |
|---|---|---|
| Read and change your data on all websites | Read, change and act on every page you open | Every bookmaker, plus your bank and your email |
| Read and change your data on a list of sites | The same, on the named sites only | Fine if the list is the bookmakers it serves, plus the site it takes selections from |
| Read your browsing history | See which pages you visit, and when | Which bookmakers you use and when you bet; Chrome shows it for the tabs permission, among others |
| Read data you copy and paste | Your clipboard | Passwords and codes you copy |
| Manage your downloads, or your apps and extensions | Act on files and on other add-ons | No betting job needs it |
Site access is the warning to read closely. With access to a bookmaker's site, an extension sees the page as you do: your balance, your bet history, and anything you type there, your password included when you log in. If it also holds the cookies permission, which shows no warning of its own, it can read the session that keeps you logged in.
Narrowing what an extension can reach
In Chrome you can set each extension's site access to work only when you click it, only on sites you list, or on all sites, from its details on the extensions page (checked October 2026). For a betting extension, list the bookmakers you use it with, plus the site it takes your selections from, and nothing else. If an update asks for a permission that triggers a new warning, Chrome disables the extension until you accept it, so read that prompt instead of clicking through.
You still click Place: where an extension ends and a bot begins
The line that matters is who completes the bet. An extension that fills the slip leaves three things with you: the decision, the stake and the click. A betting bot takes all three, whether it runs as an extension or as a program on your computer.
Racing Queensland drew the same line when it updated its minimum bet limit conditions from 1 July 2025. Its announcement of 3 July 2025 said punters will be able to use automation to select a market and add it to their bet slip. It added that this does not oblige a wagering service provider to accept a betting transaction completed by automation.
That is one racing body's conditions for its own minimum bet limits, not a national rule, but it is the same line to look for in any bookmaker's terms. Whether a tool is lawful where you live is a separate question from both, and B337 does not give legal advice.
Risk: Betting involves risk. Many bookmakers restrict automated betting and third-party access in their terms, and under them can limit stakes, void bets or close an account, so read those terms before you install any extension that works in a bookmaker's site, and above all one that places bets. See responsible gambling for limits and support.
Read the slip before you click Place
An extension carries the selection to the slip, but the price on the slip is the bookmaker's price at that moment, not the one you clicked. Prices move, and an odds board can be a read cycle behind the bookmaker, so the two can differ. With illustrative prices: you click a $4.20 win price, rate the runner's fair price at $4.00, and plan a $25 stake.
| Price on the slip | Return on $25 | Profit if it wins | Edge against a $4.00 fair price |
|---|---|---|---|
| $4.20 | $105.00 | $80.00 | 4.20 / 4.00 - 1 = +5.0% |
| $4.00 | $100.00 | $75.00 | 0.0% |
| $3.90 | $97.50 | $72.50 | 3.90 / 4.00 - 1 = -2.5% |
The 30-cent drop costs $7.50 on a winner, and it turns a price above your fair price into one below it. Some slips can be set to accept price changes without asking. With that on, the bet goes on at whatever the price is when you click, so turn it off or read the slip every time.
The slip can be wrong in other ways too:
- The tab is logged in to another account, such as a partner's on a shared computer. Only ever bet in an account in your own name.
- The runner has been scratched or the market suspended, so the slip shows it as unavailable.
- The slip already holds an earlier selection, so check it shows only the bet you mean.
- The bookmaker changed its page, and the extension added the wrong selection or none. Check the name and number.
Installing a betting extension safely
Install from a source you can trace: the browser's own extension store, under a publisher you can identify, or a download inside an account you already pay for. Never install a file sent in a chat, an email or a group. An extension added from a downloaded file skips the store's review, so the publisher has to be one you already trust and can contact.
Then match the permissions to the job. A slip filler for a handful of bookmakers needs access to those sites and to the site you choose selections on, not to all websites, your clipboard or your downloads. If it also shows "Read your browsing history", ask the publisher what it reads and why.
A slip filler works in a tab where you are already logged in, so never type your bookmaker password into a pop-up from an extension you cannot trace. If the service behind an extension asks you to link a bookmaker account with its login, ask where that login is stored, who can see it and how you remove it, the questions giving betting software your login works through.
Remove extensions you no longer use, and protect each account with a unique password and two-factor authentication where your bookmaker offers it; betting account security covers the rest.
Mistakes, and when not to use one
| Mistake | What it can cost |
|---|---|
| Granting all-sites access for a one-site job | Every page you open, your bank included, becomes readable |
| Clicking Place without reading the slip | $7.50 on the $25 example above, and a bet below your fair price |
| Leaving price changes on auto-accept | A bet at a price you never saw |
| Using an extension your bookmaker's terms forbid, above all one that places bets | A limited or closed account under the bookmaker's terms |
Skip extensions altogether on a shared or work computer, where other people use the same browser. Skip one, too, if it makes betting quicker at a time you want it to be slower: a faster slip is no help when you are betting to win back losses.
Bet Assist: the Terminal's slip filler
Bet Assist is B337's Chrome extension for the Terminal, sold as an add-on to a Terminal plan. Click a win price on the board and the race opens in your own logged-in bookmaker tab, with that runner already in your bet slip. You type the stake and click Place yourself, and B337 never places the bet. You install it by downloading it, adding it to Chrome and linking one account per bookmaker.
The Terminal behind it shows racing and sports prices from 40+ bookmakers side by side, read on a repeating cycle, so confirm the price on the slip before you place. A free account opens a limited view of the Terminal with live odds.
Risk: Betting involves risk. Bet Assist puts a runner into your bookmaker's own bet slip, and many bookmakers restrict automated betting and third-party access in their terms and can limit stakes, void bets or close an account. A price can also move between the board and your slip, and there is no guarantee of profit. See responsible gambling for limits and support.
For free and confidential support call 1800 858 858 or visit gamblinghelponline.org.au.