Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Generally, any type of work is halal so long as it does not involve haram purposes or practices.
Answering your question, the Fatwa Center at Islam Q & A, states:
By the grace of Allah (may He be exalted) to all people, and to the Muslim ummah in particular, He has made what is permissible to them broad in scope, and has made permissibility the default; He has restricted the scope of what is prohibited to the narrowest possible, and has made it rare and exceptional. He, may He be glorified and exalted, says in His wise Book:
“Allah wishes to make clear (what is lawful and what is unlawful) to you, and to show you the ways of those before you, and accept your repentance, and Allah is All-Knower, All-Wise. Allah wishes to accept your repentance, but those who follow their lusts, wish that you (believers) should deviate tremendously away (from the Right Path). Allah wishes to lighten (the burden) for you; and man was created weak.” (An-Nissa’ 4:25-27)
“Allah intends for you ease, and He does not want to make things difficult for you.” (Al-Baqarah 2:185)
“Allah does not want to place you in difficulty, but He wants to purify you, and to complete His Favour to you that you may be thankful.” (Al-Maa’idah 5:6]
Imam Ash-Shatibi (may Allah have mercy on him) said:
Hence there is nothing wrong with you freelancing in the fields you mentioned, such as graphic design, creative writing, research and development, or any other kind of creative, artistic or educational work.
What matters is that you should have a purpose in your work, whether it is to help people and make life easier for them, or to promote the values of truth, guidance and justice among them, or to teach them and increase their awareness of important issues having to do with their religious or worldly affairs.
All of these are good and valid purposes that you can undertake in the freelance work that you mentioned and other kinds of work. You may rest assured that if you bear these meanings in mind, the outcome of your work cannot be anything but good, and you will find that what you produce will fall into that praiseworthy category, far removed from the few haram matters that may be involved in such work, such as designing prohibited images, stirring up sexual desire, contributing to the spread of vile practices, selling prohibited things, and so on.
Allah Almighty knows best.