Last month I built six AI characters from scratch on six different apps. There was Mei, an architect I supposedly know from the climbing gym. Mira, a librarian with a green braid and round glasses. Maria, a painter who plays roguelike games badly. A free diver, a tram driver and an architect with curly hair rounded out the group. One took thirty seconds to make. One took most of an evening. One quietly changed details I never asked it to change.

So this is less a theory piece and more a field report. It covers how to pick a builder, what to write, what to skip and where things went wrong for me. Most of the good builders live on adult platforms, so if you would rather start from a shortlist, there is a separate roundup of AI girlfriends that are uncensored and ranked by how much freedom they give you in chat. Everything below works on SFW apps too.

What you are really building when you make one

A custom AI girlfriend is a character prompt with a face attached. Under the hood, every one of these apps runs a large language model, and your character is basically a set of instructions it reads before every reply. Writing those instructions well is a light form of prompt engineering, even if the app hides it behind sliders and buttons.

Almost every builder I used asked about the same things, just in a different order. There is the personality, which is the part that actually shapes conversation. There is the look, which only matters for pictures and the avatar. The relationship tells her how to treat you on day one. Then come the voice, a backstory or memory field, and on the better apps, a chat style setting that decides whether she texts or writes like a novelist.

Choosing the app before you build anything

This is the decision people rush, and it is the one that matters most, because you cannot move a character between apps. Here is how the builders I tried compare.

If you want the most control and do not mind spending an evening on it, Kindroid goes deeper than anything else here. If you want to shape how she writes, Egirls is the one I would point you to. If you just want to try the idea without paying anything, Xeve and AI Peeps are the easiest places to start.

Start with who she is before what she looks like

My first instinct was to open the appearance step and start clicking. That was a mistake. The portrait is what you see, but the persona is what you talk to, and a vague persona gives you a vague, agreeable character who answers everything with “That sounds amazing!”

What worked for me was writing her like a person I had met, with a job, a place, a habit and something she wants. For Mira on AniOne I started with a short bio (“a calm 26-year-old librarian who restores old maps and books”) and then clicked the Kuudere template, which filled in a reserved, dry personality I could edit. Ten minutes of editing that text made more difference than anything I chose later.

A few things that made my characters noticeably better:

• Give her a flaw or a want. “Competitive, hates losing at bouldering” beats “kind and funny” every time.
• Be specific about places and objects. A city, a job and one odd hobby give the model something to pull from.
• Describe how she talks, not just what she is like. Short and dry? Warm and rambling? Teasing?
• Leave room. A persona that scripts every reaction tends to make a character that repeats herself.

Deciding how she talks to you

This is the setting I wish every app had. Egirls asks you to choose between a roleplay style and a texting style, and it shows a sample of each so you can see the difference before choosing. It also asks for reply length and a writing level, from chill to creative. I set Mei to roleplay, medium length, creative, and her replies came back as little scenes with actions and dialogue rather than one-line texts.

If your app does not have a setting like this, write it into the persona instead. A line like “replies in two or three short messages, like texting a friend” does a surprising amount of work.

Getting the look right

Here the main choice is realistic or anime, and then presets or a written description. Presets are faster and more consistent. Descriptions give you more control but can drift.

AniOne handled descriptions best in my tests. I typed “long dark green hair in a loose braid, round glasses, amber eyes, cream knit cardigan” and paid one token for a test image. The preview matched every detail, which saved me from creating the character and regretting it.

FlirtCam went the other way, with a huge menu of options (sixteen hair styles, sixteen colours, facial hair and eye colour) and a button to randomize the lot if you cannot decide. For a male character it felt like a proper character creator in a video game.

Giving her a voice

Most builders now include a voice step, usually with a handful of presets you can play before choosing. Xeve gave me four voices on the same screen as the relationship setting, which ranges from stranger to wife. Egirls offers three, AniOne five.

AI Peeps goes further. Its Voice Studio can clone a voice from a short audio clip or build one from a written description, which took about fifteen seconds when I tried it. Only clone your own voice or one you have permission to use.

Making sure she remembers you

A character who forgets your name by Thursday is not much of a companion. The fix is to put the important things where the app reads them every time, rather than hoping she picks them up in conversation.

Kindroid is the best at this. It has a backstory field of up to 2,000 characters, a separate greeting, and on top of that key memories and response directives that you write yourself. On other apps, the persona or “identity” field does the same job. I put my job, my city and the names of people I mention often into that field, and stopped having to repeat myself.

A step by step walkthrough you can follow on any app

1. Pick the app based on what you want most, whether that is writing, pictures, voice or price.
2. Write a two-line bio with a job, a place and something she wants.
3. Choose a personality template if there is one, then edit the text until it sounds like a person.
4. Set the chat style and reply length, or describe them in the persona.
5. Choose the look and voice, and use any preview the app offers.
6. Fill in the backstory or memory field with the facts she should always know.
7. Pick a starting relationship. I started most of mine as friends, which gave the first chats somewhere to go.
8. Review every field before you create her, especially anything a randomize button touched.

Where it went wrong for me

AI Peeps taught me the most expensive lesson, even though it cost nothing. Its builder has randomize buttons that fill every field, and I did not clear them all. My tram driver, written as a 34-year-old from Budapest, came out listed as 21 and American, with a halo and wings I never chose. Now I check every field before I press create.

FlirtCam's preview got stuck at 92 percent on my first character. The character was created anyway and worked fine, so I would not panic if it happens to you. AIMOUR was the most expensive builder by far, at 500 tokens per character plus 100 more to keep her private. The result looked like what I asked for, but it is not a place to experiment casually.

Keeping it private and on the right side of the line

Most builders let you keep a character private, and I would do that by default, especially if your persona includes details about your own life. Flirtzy, for example, publishes characters you create, which is fine for a fantasy elf and less fine for a character built around your actual job and city.

The other line is real people. Do not upload a photo of someone you know, or recreate a celebrity or an ex, without their consent. Apart from being unkind, it moves into the territory of deepfakes, which is illegal in a growing number of places. Reputable apps require characters to be adults and will remove ones that are not.

Questions people usually ask

Can I make a custom AI girlfriend for free?

Yes. Kindroid, Xeve and Soulkyn let you build for free, AI Peeps allows two free creations a day, and FlirtCam does not charge tokens to create. Talking to her at length usually needs a paid plan.

How long does it take?

About thirty seconds on Xeve, around four minutes on AniOne, and anything up to an evening on Kindroid if you fill in the memory properly.

Can I change her after I create her?

Most apps let you edit the persona and details later, though how much varies. Check the edit options before you put hours into a first build.

Can I make an anime AI girlfriend?

Yes. AniOne is built around it, and Egirls, Nomi, Soulkyn and AI Peeps all have an anime style option.

Will she remember what I tell her?

Within a conversation, the apps I tested did. For things she must remember long term, put them in the backstory, persona or memory field.

Can I base her on a real person?

Not without that person's consent. Use your imagination or the app's presets instead.

If you only try one

Start small. Pick one app, write a short persona with a job, a place and a want, choose a voice, and give her a backstory with the three facts you care about most. Talk to her for a week before you start tweaking. The characters I liked most were not the ones with the most settings filled in. They were the ones where I spent ten extra minutes on the persona text.