SaiWorn out by people?
Journal your feelings person by person
The same day can feel completely different depending on who you spent it with. Sai keeps a separate emotional record for each relationship, and once you have 3 entries, AI calmly maps how the relationship is going—and who you are within it.
- Free to start
- Guest access
- 6 languages
Not just “me today,” but “me with them”
The biggest difference from a regular diary app is what each entry is about.
“How did I feel today?”
Regular diary apps
Entries are organized by day. Who each moment was with gets mixed up, and recurring relationship patterns stay hidden.
“Why do I act like this only around them?”
Sai, the relationship journal
Record feelings, body sensations and defense mechanisms for each person. How you react differently—and what keeps repeating—naturally comes into view.
Three simple steps
No essays required. From a single tap to an honest entry, write at your own pace.
Add a relationship
Add someone you want to understand better and pick a character that matches how things feel right now.
Record feelings
Log just your mood in 3 seconds, or work through your feelings step by step in a 4-step entry.
Get AI insights
Once a relationship has 3 entries, AI analysis unlocks: the relationship's flow, you in the relationship, and Mind Talk.
The more you record, the clearer it gets
Sai is designed to record and reflect on feelings within the context of a relationship.
3-second quick log
On days when writing feels like too much, just tap your mood. Even light entries become material for analysis.
Body cues & defenses
Alongside emotions, note body sensations, tension and defense mechanisms like denial, avoidance or rationalization.
Emotion timeline per person
See entries and mood changes for each person at a glance, with a summary of your most frequent emotions and defenses.
AI relationship report
Based on recent entries: positive and negative interaction keywords, relationship score and distance trend, and concrete next steps.
Me in Relation (AI persona)
Explore your behavior patterns in that relationship, the defenses you use most, sensitive spots, and suggested healing actions.
Mind Talk
Choose a theme—Look back, Reflection, Regrets, Gentle prescription or Breathing room—and receive a warm message tailored to your entries.
Swipe to see more screens
What does your relationship look like right now?
When you add a relationship, pick a character that reflects it. You can change it any time as things evolve.
SunnySomeone who makes your heart feel warm
SteadySomeone you can count on to be on your sideBubblySomeone you can laugh and joke withBloomSomeone you would like to get closer to
ShyA connection you are still getting comfortable with
PricklyA connection where you want to take care before opening up
MistyA connection that feels more distant than before
SparkyA connection where different opinions often clashCare for yourself beyond relationships
Besides relationship entries, Sai offers small tools to look after your mind.
Personal diary
A private space to step away from relationships and listen to how your own day felt.
Article Hub
From family, partners and work to stress, sleep and self-esteem—read articles that support recovery, bookmark them and keep private notes.
Guest access
Start right away without signing up. If you like it, link a Google or Apple account to keep your entries safe.
6 languages · MBTI-aware
Available in Korean, English, Japanese, Traditional Chinese, German and Spanish. Add your MBTI to tailor greetings and analysis tone.
No payments—just free credits
Every AI analysis and message has a real cost. Instead of charging you, Sai covers it with ad revenue.
Earn credits
- Welcome bonus1,000
- Daily check-in (once a day)+50
- Rewarded ad (2× a day)+100
- Rewarded interstitial ad (3× a day)+50
Use credits
- AI relationship report200
- AI persona (Me in Relation)200
- Mind Talk (per theme)100
- If an AI request failsNot charged
Credits cannot be bought or exchanged for money, and amounts may change as the service evolves. You can turn the confirmation prompt on or off in settings.
Your entries belong to you
So you can write honestly, we keep clear rules about how your entries are handled.
Only you can see them
Entries are stored in your account and protected by security rules so only you can access them. The people you add are never notified.
AI only when you ask
Relevant entries are sent to Google Vertex AI only when you request an analysis, and they are not used to train AI models.
Never used for ads
Your entries and diary are never used for ad targeting or sold. Personalized ads appear only if you consent.
Delete any time
Delete individual entries, relationships or reports, or request account deletion: recoverable for 30 days, permanently deleted after 90.
Sai is not a medical service. AI results are reference information based on your entries and do not replace professional diagnosis, counseling or treatment. If you are thinking about harming yourself or are in crisis, please contact your local emergency number or a crisis line right away (e.g. 988 in the US, 116 123 in the UK & Ireland).
Questions?
Is it really free?
Yes. Downloading and journaling are free. AI features use credits from the welcome bonus plus free credits you earn through daily check-ins and rewarded ads. There are no paid purchases.
Can I use it without signing up?
Yes—tap “Guest access” to start right away. Note that signing out of guest mode deletes your data immediately, so if you plan to keep using Sai, link a Google or Apple account from My page.
Will the other person find out?
No. Sai never contacts or notifies the people you add, and your entries are visible only in your own account. We also recommend using a nickname rather than someone's real name.
When can I use AI analysis?
Once a relationship has 3 or more entries, “Relationship analysis” and “Me in Relation” unlock. “Mind Talk” becomes available once that relationship has an analysis report.
Is my data used to train AI?
No. AI features run on Google Vertex AI (Gemini). Only the entries needed for your request are sent, and they are not used for model training. See the Privacy Policy for details.
What happens if I delete my account?
Schedule deletion in the app under Me › My page › Delete account. Sign in again within 30 days to restore it; after 90 days everything is permanently deleted. Read the account deletion guide for details.
Which languages are supported?
Korean, English, Japanese, Traditional Chinese, German and Spanish. You can switch languages inside the app.
Is someone on your mind today?
Write one line about today with them. As entries add up, the space between you becomes a little clearer.