Das Lesezeichen hilft mir, auch wenn ich zu viele Tabs offen habe.

Because helfen is one of the German verbs that takes a dative object, not an accusative one.

• jemandem helfen = to help someone
• So mir is the dative form of ich

Quick comparison:

• Er hilft mir. = He helps me.
• Er sieht mich. = He sees me.

With sehen, German uses the accusative (mich). With helfen, it uses the dative (mir).

Das Lesezeichen means bookmark.

In modern German, it can mean:

• a physical bookmark in a book
• a browser bookmark in a computer or phone context

Since the sentence talks about Tabs, this is clearly the browser bookmark meaning.

Also:

• singular: das Lesezeichen
• plural: die Lesezeichen

Auch wenn means something like even if, even when, or although depending on context.

In this sentence, it introduces a contrast:

• Das Lesezeichen hilft mir = the bookmark helps me
• auch wenn ich zu viele Tabs offen habe = even if/even when I have too many tabs open

So the idea is: the bookmark is helpful despite that situation.

A useful comparison:

• wenn = if / when
• auch wenn = even if / even when
• obwohl = although

In many everyday sentences, auch wenn and obwohl can feel similar, but auch wenn often highlights a condition or circumstance more strongly.

Because auch wenn introduces a subordinate clause, and in German subordinate clauses, the conjugated verb usually goes to the end.

Main clause:

• Das Lesezeichen hilft mir.

Subordinate clause:

• auch wenn ich zu viele Tabs offen habe

So instead of the normal main-clause order, German pushes the finite verb habe to the end.

This is a very common rule after words like:

• weil = because
• dass = that
• wenn = if/when
• obwohl = although
• auch wenn = even if/even when

Both patterns exist, but they mean slightly different things grammatically.

1. Ich habe viele Tabs offen.

This means I have many tabs open.
The subject is ich, and the tabs are something I currently have open.

2. Viele Tabs sind offen.

This means Many tabs are open.
Now Tabs is the subject.

German often uses haben + adjective for this idea:

• Ich habe die Tür offen. = I have the door open.
• Sie hat das Fenster zu. = She has the window closed.
• Ich habe zu viele Tabs offen. = I have too many tabs open.

So offen haben is a very normal German structure.

Because offen is not being used here as an attributive adjective before the noun. It is functioning more like a predicate adjective.

Compare:

• offene Tabs = open tabs
  Here the adjective comes before the noun, so it takes an ending.

• ich habe Tabs offen = I have tabs open
  Here offen describes the state of the tabs, so it does not take an ending.

This is similar to:

• ein offenes Fenster = an open window
• Das Fenster ist offen. = The window is open.
• Ich habe das Fenster offen. = I have the window open.

Zu viele means too many.

• viele Tabs = many tabs
• zu viele Tabs = too many tabs

The word zu here expresses excess.

Examples:

• Ich habe viele Bücher. = I have many books.
• Ich habe zu viele Bücher. = I have too many books.

So the sentence is not just saying there are many tabs, but that there are more than is convenient or desirable.

In zu viele Tabs, viele is part of a plural noun phrase, and in the nominative and accusative plural, forms like viele often appear without an extra ending.

So:

• viele Tabs = many tabs
• zu viele Tabs = too many tabs

This is normal.

Compare:

• Ich sehe viele Tabs.
• Ich habe zu viele Tabs offen.

But in other cases you may see endings elsewhere in the phrase, for example:

• mit vielen Tabs = with many tabs

There, vielen is dative plural.

Tabs is in the accusative plural here, because it is the direct object of haben.

The basic structure is:

• ich habe was? → zu viele Tabs

So:

• subject: ich
• verb: habe
• direct object: zu viele Tabs
• state/complement: offen

Since Tab is a masculine noun (der Tab), the plural is:

• singular: der Tab
• plural: die Tabs

In this sentence, the plural form Tabs stays the same in nominative and accusative.

Because auch wenn ich zu viele Tabs offen habe is a subordinate clause, and German normally separates subordinate clauses from the main clause with a comma.

So:

• Das Lesezeichen hilft mir, auch wenn ich zu viele Tabs offen habe.

This is standard German punctuation.

You will see the same thing with many other subordinate-clause starters:

• ..., weil ich müde bin.
• ..., dass er kommt.
• ..., wenn du Zeit hast.

Because in German, all nouns are capitalized, including borrowed words from English.

So even though Tab comes from English, in German it behaves like a regular noun:

• der Tab
• die Tabs

That is why it is written with a capital T in the sentence.