Spanish Translation Engines

Google Translate Tool - Translate text or a web page from Spanish to English, or English to Spanish, plus a number of other languages. Links in the page translated with the web page translator will also render in the new language.
Translated.net Online Translation Engine - Translation service with free online translations of text from Spanish to and from English, Chinese, French, German, Greek, Italian, Japanese, Korean, Portuguese, and Russian, with a large variety of technical and specialty lexical databases.
Dictionary.com Translation Engine - Translate text from Spanish to English and vice-versa, plus a number of other language combinations.
ProMT Online Translation Engine - Provides online translations for Spanish-English and English-Spanish, with a number of other language options; also displays back-translation of the translated text.

 

 

  Spanish Dictionaries

Diccionario de la Lengua Española - Searchable online version of the 23rd edition of the Diccionario de la lengua española, a comprehensive monolingual Spanish dictionary.
Diccionarios Académicos - Searchable online interface to the Diccionarios Académicos, a monolingual academic Spanish meta-dictionary that provides access to numerous famous dictionaries of the past (from 1726 to 1992) in graphics facsimile format.
Diccionarios.com - Translations, definitions, and phrasal verbs for Spanish to and from English, French, German, Catalan to and from Castilian; Spanish synonyms and antonyms.
American Heritage Spanish Dictionary, 2nd Edition - Bilingual Spanish-English dictionary featuring American English and Latin American Spanish; contains 70,000 entries, with more than 120,000 meanings.
SpanishDict.com - Spanish-English bilingual dictionary with 56,000 entries with over 10,000 audio pronunciations; plus word of the day.
LookWAYup Dictionary - Spanish-English dictionary, also includes English-Spanish; click "More" for thesaurus and synonyms; double-click a word in the definition to define it.
Word Reference Spanish-English Dictionary - Bilingual Spanish-English dictionary with downloadable translation toolbar.
LingvoSoft Spanish-English Online Dictionary - Bilingual Spanish-English dictionary; site also includes a multilingual dictionary with 25 languages.
Freedict Spanish-English and English-Spanish Dictionary - Simple word translations without additional information.
Ectaco Online Spanish-English Dictionary - Spanish-English bilingual dictionary; site also includes 21 other languages.
Dict.info Spanish Dictionaries - A collection of free Spanish bilingual dictionaries for English, Czech, Esperanto, French, German, Russian, Slovak, and Swedish. Browsable online, with word searches, and downloadable data files.
TriTrans - Translates words between Spanish, English and Norwegian.
myjmk.com German-Spanish Dictionary - Online searchable bilingual German-Spanish dictionary with large dataset (over 121,000 terms).
Pauker German-Spanish Dictionary - Online meta-dictionary search for German words and their Spanish equivalents.
Szotar Spanish-Hungarian Dictionary - Online bilingual Spanish-Hungarian dictionary; interface in Hungarian.
123teachme Spanish Medical Dictionary - HTML Spanish-English medical dictionary
Medical Spanish Dictionary - "Click on one of the above medical Spanish dictionaries to look up Spanish medical terminology. Translations include coloquial usage, and all terms inlcude audio."
List and Glossary of medical terms: Spanish - Online medical glossary for a number of languages

 

 

  Regional Dialects and Slang

Jergas de Habla Hispana - An extensive online dictionary of the Spanish slang of Spain and Latin America. Terms can be sorted by country of use, with words common through the Spanish-speaking world cross-referenced; also included are comparative examples of sentences, using the slang typical of each Hispanic country.
Diccionario Argentino-Español - HTML glossary of Argentinian Spanish.
Diccionario del Español usual en México - Online HTML glossary of Spanish terms as they are used in Mexico, compiled by Luis Fernando Lara.
Diccionario des Modismos - Searchable and browsable dictionary of Chilean Spanish idioms and words.

 

 

  Medical and Technical

Medical Spanish Dictionary - "Click on one of the above medical Spanish dictionaries to look up Spanish medical terminology. Translations include coloquial usage, and all terms inlcude audio."
Diccionario medico-biologico, historico y etimologico - Spanish dictionary of biological and medical terms, with historical background and etymology
123teachme Spanish Medical Dictionary - HTML Spanish-English medical dictionary
List and Glossary of medical terms: Spanish - Online medical glossary for a number of languages.
Andy Miles English-Spanish Business Dictionary - With over 6000 terms.
Comparative CyberLexicon - Compilation of English terminology peculiar to computer culture and technology and its equivalents in Spanish.