
tonnenweise
tons of
Colloquial and exaggerated for a very large, countless amount of something.
Für die Party haben wir tonnenweise Chips und Getränke gekauft.
For the party, we bought tons of chips and drinks.
by the ton / tons of
Loading your saved state.

tons of
Colloquial and exaggerated for a very large, countless amount of something.
Für die Party haben wir tonnenweise Chips und Getränke gekauft.
For the party, we bought tons of chips and drinks.

by the ton
In an amount measured in tons.
Die Fabrik verarbeitet tonnenweise Stahl pro Tag.
The factory processes steel by the ton every day.
The word consists of 'Tonne' (ton) and the ending '-weise'. This ending forms adverbs with the meaning 'in the manner of ...', so here literally 'in the manner of tons'.
Nach dem Sturm lagen ästeweise Blätter auf der Straße.
After the storm, leaves were lying on the street in piles.
'Tonnenweise' (by the ton/tons of) is an adverb and is never declined. Its form always stays the same, no matter which noun it refers to.
Im Herbst gibt es hier tonnenweise Äpfel zu ernten.
In autumn, there are tons of apples to harvest here.
In the meaning 'sehr viel' (a lot), 'tonnenweise' (tons of) is colloquial and a strong exaggeration. It is used in informal conversation to emphasize a huge amount.
Ich habe noch tonnenweise Arbeit zu erledigen, bevor ich in den Urlaub fahren kann.
I still have tons of work to do before I can go on vacation.
The literal meaning is used in technical or industrial contexts (e.g., with steel, coal, grain). The figurative, colloquial meaning is found in everyday language for almost anything (e.g., homework, money, problems).
Das Schiff transportiert tonnenweise Eisenerz.
The ship transports iron ore by the ton.
massive / in large quantities
Both words can express a huge quantity. Massenhaft tends to emphasize that many individual things or people are present, whereas tonnenweise is colloquial and exaggerated, highlighting the enormous quantity. Massenhaft suits many individual occurrences, while tonnenweise is more of a figurative quantity expression.

Auf dem Markt lagen tonnenweise reife Äpfel in den Kisten.
Tons of ripe apples lay in crates at the market.
Auf dem Markt lagen massenhaft reife Äpfel in den Kisten.
Huge numbers of ripe apples lay in crates at the market.