Marathonbet Bonus Code WELCOME100 opens a 500% deposit bonus and 300 free spins for new casino accounts, and the whole thing can be claimed from a phone if you know where the code field hides on a small screen. The 500% is not one match — it accumulates across five separate deposits, each matched at 100% up to a per-deposit ceiling of €1,000, which means the mobile journey is not a single form but a sequence you return to over several days. That changes what matters on mobile: not just typing the code correctly once, but keeping track of tiers, spin credits and a clock that keeps running whether your phone is in your pocket or not.
App or mobile browser: which to register in
The safest route is the one the source of the offer points to: open the official Marathonbet site and begin registration there. A mobile browser gives you the full registration form, including the optional fields that apps sometimes condense or reorder, and it lets you see the offer selection screen where the casino welcome package sits alongside the sports one.
If you prefer an app, the general rule with any operator is that a bonus code entered in the app and a bonus code entered on the site are handled by the same account system — the difference is layout, not entitlement. What varies is whether the app's signup flow exposes a promo code box at all. Some mobile signup flows trim the form down to the legal minimum and push promotions to a post-registration screen. If you cannot find the field, do not register and hope to add the code later; back out and complete signup in a mobile browser where the field is visible.
One practical point in favour of the browser on first signup: you will also be selecting your account currency, and that usually cannot be changed afterwards. A wider layout makes it harder to tap the wrong dropdown entry by accident.
Where the code field actually lives on a small screen
On desktop, a promo code box normally sits in plain view beside the password and personal-details fields. On a phone, the same form is stacked vertically, so the box is often several scrolls below the fold. Typical places to look:
Near the bottom of the registration form, under the address and date-of-birth fields, sometimes collapsed behind a line such as "Have a promo code?"
Behind an expandable arrow or plus icon that looks like a formatting element rather than an input
On a second registration step, after the personal details step has been accepted
On the offer selection screen, where choosing the casino welcome package reveals the code box beneath it
Scroll the whole form to the end before submitting anything. Mobile keyboards cover the lower third of the screen, so a field can be fully rendered and still invisible while you are typing in the field above it. Dismiss the keyboard, then scroll again.
Entering WELCOME100 without the phone getting in the way
Mobile keyboards are the single most common reason a valid code appears to be rejected. Three specific behaviours to watch:
Autocapitalisation and autocorrect can rewrite a code that mixes letters and digits. Type WELCOME100 manually, then read it back character by character before submitting.
Copy and paste often carries a trailing space from wherever you copied it. A space is a character, and some forms treat the string as invalid because of it.
Password managers and browser autofill sometimes drop an unrelated value into an empty field they mistake for a username. Check the box contains the code and nothing else.
Open the official Marathonbet site in your mobile browser and start registration.
Scroll the form to the end and locate the bonus or promo code field, expanding any collapsed section.
Enter WELCOME100 and confirm the characters are correct with the keyboard dismissed.
Select the casino welcome offer rather than the sports offer — the two are separate and you generally cannot hold both.
Set your account currency deliberately, since it usually cannot be changed later.
Deposit at least the stated minimum, reported at around €5, to trigger the first tier and its 100 free spins.
Open the wagering tracker before placing any bet, and complete identity verification straight away rather than waiting until withdrawal.
The staged structure, viewed from a phone
The first deposit is matched 100% up to €1,000 and carries 100 free spins. Deposits two through five are each matched 100% up to €1,000 and carry 50 spins each, which is how the package reaches up to €5,000 in bonus credit and 300 spins in total. Reaching that ceiling means depositing €5,000 of your own money across five transactions.
Because the minimum is low, the package scales down to whatever you actually deposit. A €50 deposit produces a €50 bonus, not €5,000. On mobile this matters for a specific reason: depositing is quick on a phone, and five quick taps over five days feel smaller than one large transfer. Decide the total you intend to commit before the first tier, not after the third.
Rollover and the clock, tracked on a small screen
Bonus credit is reported to carry a 35x wagering requirement cleared on slots, and free-spin winnings carry a separate 30x requirement. The arithmetic is what decides whether the package is realistic:
A €20 deposit gives a €20 bonus, so 35x is €700 in qualifying wagers — a single session.
A €200 deposit gives a €200 bonus, so 35x is €7,000.
A €1,000 first deposit gives a €1,000 bonus, so 35x is €35,000.
All five tiers at the ceiling implies €175,000 in cumulative turnover.
The reported window is around 14 days from crediting, and the clock starts when the bonus is credited rather than when you first play. Turnover counts cumulative stakes rather than losses, but every wager pays the house edge, so a longer grind leaves a smaller expected balance at the end.
Two mobile habits help here. Bookmark or pin the bonus and wagering page so the tracker is one tap away rather than buried in a hamburger menu. And keep push notifications enabled if the operator uses them for bonus credits and expiry, because spins arriving across five deposits over several days are the easiest part of a staged package to lose track of — and spins commonly expire on their own schedule.
Mobile quirks that can void the bonus
Most of the restrictions are identical whatever device you use, but a phone makes some of them easier to trip.
Maximum bet. There is a per-spin cap while a bonus is active, and exceeding it even once can void the bonus and all progress. Stake sliders on small screens are fiddly; set the stake and check it before spinning.
Game weighting. Slots typically contribute in full while table and live games contribute little or nothing, so a bonus played on the wrong section moves slowly if at all.
Excluded titles. Certain high-return slots and bonus-buy features are commonly barred during wagering, and mobile lobbies often surface recommendations that sit outside the eligible list.
Spin allocation. The 300 spins are tied to specific slot titles chosen by the operator, not a game of your choosing, so search for the named title rather than a similar one.
One per household. Duplicate accounts sharing an address, device or payment method are routinely detected — including a second account created on the same handset.
Where mobile helps and where it does not
In its favour: the low minimum means the small end of the package is genuinely clearable, rollover applies to the bonus rather than deposit plus bonus, spins are spread across five tiers instead of one drop, and Marathonbet has traded since 1997. On a phone, a €20 to €100 deposit with a €700 to €3,500 requirement is a target you can monitor between other things.
Against it: the 500% headline needs €5,000 of your own deposits, the 35x bonus requirement and the 30x spin-winnings requirement are two separate obligations to track on a screen that shows one thing at a time, spins are locked to operator-chosen games with their own expiry, and a roughly two-week window is tight for anything beyond a small deposit. The casino and sports welcome offers are also mutually exclusive, and on mobile the offer selection step is easy to swipe past without reading.
Before you tap deposit
Work forwards from the amount you are willing to deposit and calculate the requirement it creates, rather than backwards from the advertised ceiling. Then confirm the live terms on the offer page at opt-in, since staged packages are adjusted by market and campaign more often than most promotions — and on mobile the full terms usually sit behind a link that is easy to scroll past.
Gambling involves risk and is intended for adults aged 18 or over (or the legal age in your jurisdiction). Bonuses carry wagering requirements — read them in full before opting in, never stake more than you can afford to lose, and seek support if gambling stops being entertainment.
Promotional terms, eligibility and values are set by the provider and can change at any time. Always confirm the current terms on the official site before signing up or completing a purchase.