Where can I find all Hitler speeches in original German?

A reliable and complete one-stop historical-critical collection of all speeches is still to be made.

You can consult lots of collections, also online. But only for parts of different timeframes are there collections of varying quality.

Below you'll find:

1. 1922–1924: one highly dubious but still unique collection, compiled by a nazi, published in 1925
2. 1925–1933: one rather excellent, recent, high quality, historical-critical, multi-volume work, compiled and commented by proper historians, published mainly in the 1990s
3. 1933–1945: one slightly older collection that has been highly praised, but one that is coming with some often overlooked drawbacks. A collection of 4 volumes, often cited, but much more limited in its utility than the effort that went into it and the praise it initially got might suggest, compiled by one historian, first published in the 1970s

Google indeed is a full-on censorship bubble producer and thus not to be trusted as the sole search engine to use. Crucially: This concerns every topic. Use only Google and get your world distorted.

But the first alternative search engine I just tried reveals for example this collection, on archive.org:

— Max Domarus (ed): "Hitler Reden und Proklamationen 1932–1945, Vol 1–4 (komplett)", Leonberg: Pamminger & Partner, 1987.

This collection is 'fairly' comprehensive for the named in title timeframe, although it needs to be treated with some scrutiny. Some rather glowing reviews of this work.

But the drawbacks for this are summarised as:

Contrary to what most people think this is not a complete collection of complete speeches. Some speeches are mere excerpts. Others are missing altogether. Even worse is the fact the confused editorial structure of the book. It is often hard to see where speeches begin and end, and Domarus insists on inserting his comments in the middle of speeches. The main value of the book is that it is a good list of Hitler's speeches and footnotes for those speech listings.

The English translation is a particular problem being of very poor quality.

— World Future Fund: "The Speeches of Adolf Hitler. Problems In The Documentary Record", which also hosts "Some Key Speeches Of Adolf Hitler. Complete Text In English And German".

Unfortunately, that just used site also suffers from some of its very own problems, like how they arrive at the above assessment, or their lacking modified-dates on their pages…

That the criticisms from World Future Fund are generally correct however can be demonstrated in examples: that person gave a speech on November 8, 1940 in Munich's Löwenbräukeller, to commemorate the Putsch of 1923. Domarus references his source properly, but when comparing his printed and amply commented mid-stream version with a version of that speech published at the time in Der großdeutsche Freiheitskampf (DGFK: a collection publication from 1943), we see a few minor in length but not so minor in their implications missing in Domarus: namely that the DGFK has a passage with allusions to the extermination of the Jews.

This can be checked when reading along to that persons speeches the excellent collection about then recent scholarship on the subject:

— Josef Kopperschmidt & Johannes G. Pankau (ed): "Hitler der Redner", Wilhelm Fink Verlag: München, 2003. The DGFK bit in chapter Christoph Sauer: "Rede als Erzeugung zum Komplizentum": p.422. (online PDF BSB/MDZ)

Now, it may be argued that Domarus source Deutsches Nachrichtenbüro indeed omitted this 'little detail' in its original publication in 1940, before Wannseekonferenz and Final Solution, and that this passage was re-introduced to the text for the DGFK publication 'after Wannsee'. But what words were actually spoken at the time when the speech was held? From Domarus alone, you won't know. So that source needs to be treated with critical care.

To avoid this censorship problem in search engines hindering research —for now— use not just censoring Google, but other general search engines as an alternative. Not everything is indexed by those engines anyway. Further: go into the search engines of individual databases or libraries. Those information systems reveal a whole other world than generalised internet search engines, who are restricted not only due to pervasive censorship, but also in what they can index.

For the question at hand of "all speeches": For quite a while this person was something like a loud-mouthing nobody, and therefore not really all speeches survive. Hist first speech was allegedly merely three minutes long in a beer hall. Additionally, between 1925 and 1927 he was legally prohibited from making any public speeches at all. There are significantly more than 1500 known public speeches — according to Wikipedia: 'List of speeches given by Adolf Hitler' …

Keep in mind that this person was also prone to give impromptu 'speeches' at inconvenient times. That is, when others around him were just waiting for their soup or cake. Although there are some collections out there that claim to have these 'speeches' transcribed, and 'show the Führer in private', those are all not trustworthy sources. But they are conveniently easily locatable as 'Table Talk' and the like.

With this caveat in mind, the earlier speeches are for example for the most part collected in:

— Clemens Vollnhans, Institut für Zeitgeschichte (ed, other main editors for other volumes): "Reden, Schriften, Anordnungen: Februar 1925 bis Januar 1933", K.G. Saur: München, multiple Volumes, 1992–2003. (More than a dozen thick volumes, pricey as on-demand hardcovers, but two sources for them on archive.org: 1, 2.) This is a reliable, historically critically source edition.

From the website of the publisher:

The edition of speeches, writings and orders makes all of Adolf Hitler's surviving statements from the re-founding of the NSDAP in February 1925 to his appointment as Reich Chancellor on 30 January 1933 accessible to historical research and the interested public.

An earlier and shorter collection would be:

— Erhard Klöss (ed): "Reden des Führers: Politik und Propaganda Adolf Hitlers 1922–1945", dtv: München, 1967.

Going still further back, we get into the troubled waters of original nazi publications, as I don't know historical critical editions for those:

— Ernst Boepple (ed): "Adolf Hitlers Reden", Deutscher Volksverlag: München, 1925. (For the time frame 1922–1924. 17 'speeches' and some 'aphorisms', 127 pages. Given the editor and publisher: handle with even more extra care! And notice that Wikipedia gives a list of some of his publications, but not the speeches just listed. One version is on archive.org.)

If anyone happens to circumvent the generalised censorship problem on this topic, finds a neo-nazi or plain nazi site that mirrors for example 'Neuschwabenland-Archiv', 'Neues Europa', 'Hitler-Archive', 'das-reich', or 'der-fuehrer' (and more…, links to working sites omitted on purpose) then one rule of thumb needs to be used: 'original scans' of the original printed material of the nazi pamphlets and books are usually 'reliable', and if treated as primary source material in this sense an 'OK' starting point. But it seems that everything with a publication date after May 1945 on those servers is a further step down on the quality ladder, and again at best usable as primary source material for that timeframe, with additional heaps of salt needed, but not really for anything about the inquired timeframe.

That those sites often do include a copy of Domarus —despite neo-nazis often disliking it and accusing Domarus of 'smearing the Führer's image and personality'— should cast as much doubt on the overall reliability and quality of Domarus as the names used for the glowing reviews and testimonials linked above. Hitleristic scholarship resting on what Trevor-Roper found 'very good'? The English speaking world still pretty much loves Domarus' edition, and it can be used, but as with 'Google as a sole search engine', Domarus as the sole source used uncritically for the speeches is a bad idea. Despite it still being 'the best collection' for the timeframe, it serves best as a starting point to go at all those sources listed in it.