Underfiction vs Slowburn

Slowburn, at slowburn.chat, is a web platform for long-form AI roleplay built by two independent developers, with a tagline about stories and characters that value the buildup. Its opening claim is an AI that isn't pinning you against the wall by turn five. Anyone who has watched a model confess undying love on turn six knows that complaint is legitimate, and Slowburn is right to build a product around it.

We make Underfiction, so read this as one indie shop looking at another. We share the complaint. We answered it differently. Everything below about Slowburn comes from its public pages as of September 2026; where the site is silent, we say so rather than guess.

What Slowburn gets right

The structure is persona and character: you play a persona, the AI plays a character, and you put the two of them in a story. Memory is the thoughtful part. Seeded memories are the ones you write in up front; earned memories accumulate as you play; old ones fade and related ones consolidate into beliefs. A chapter is a jump in time or place inside the same story, and you can fork any chapter, or any single message, into an alternate track while the original stays untouched. That is a real design, not a chat log with a summary bolted on.

The free tier is generous for a two-person operation paying inference bills. Spark gives you fifty messages a day, resetting daily, described as full content with no caps on what you make. Hit the limit for the first time and you get three days of the Blaze tier on the house, no card required.

What it keeps behind the curtain

Models. Slowburn does not say what writes the prose. You pick a voice by temperament: Kindling is fast and in the moment, Ember is slower and more considered, Cinder is terse and gritty and reserved for paid plans. The heavier voices cost more of your daily allowance. You can supply your own model key if you have one, which is a good escape hatch, but the default experience is a black box with a mood label on it.

Prices are behind sign-in too. The paid tiers are Candlelit, Blaze and Bonfire, and the public wiki describes what they add, a larger daily allowance, the Cinder voice and longer replies, without a number next to any of them. Content limits work by tag: you set a content tier, and the lowest tier of any tag you apply becomes the floor. A content policy page exists. What it actually permits is not spelled out on the pages a visitor can read before creating an account.

Why we keep pressing on model names: the prose you get is the model you get. When whatever sits under a voice gets swapped or throttled, the writing goes flat and you have no way to know why. Underfiction's picker shows real model names, frontier models next to uncensored open-weights options, switchable on any turn, and a retired model keeps its real name in the story's history so a turn always says what wrote it.

Pricing, two philosophies

Slowburn meters messages per day and sells subscriptions that raise the meter. Underfiction sells credits spent per generated word, with no subscription, no daily counter, and no expiry; a new account gets five hundred credits after email confirmation. A heavy daily writer can come out ahead on a flat plan, and fifty free messages are hard to argue with. A few evenings a week is a different sum: a meter that resets whether or not you touched it is paying for someone else's Tuesday.

Pacing, the thing they are named for

Credit where it is due: Slowburn built the whole product around not rushing, and if you want a slow burn by default with nothing to configure, that is a coherent offer. Underfiction treats pace as a direction. Narration nudges set interiority, point of view and length; standing directions in your own words are injected on every turn; and stepping outside the scene to tell the narrator to hold the tension for another chapter takes one line. The difference is who decides. Slowburn decided for you and decided well. We hand you the dial, because the same reader who wants a forty-turn courtship on Monday wants the door kicked in on Friday.

So which one?

Pick Slowburn if you want a browser-only roleplay app whose defaults already match your taste, a free daily allowance you will actually use up, and a memory model with forks you can wander through. It is a serious indie product and the two people behind it clearly read.

Pick Underfiction if you want to know which model is writing and to change it mid-scene, if you want the same story on your phone as a native app, if images and video belong inside the story for you, or if you want to pay for the words you wrote and nothing else. Bring a character card over and give the same scene to both. The prose will tell you faster than we can.

Underfiction is interactive storytelling under your direction. Stories sync across devices, encrypted at rest, and one switch keeps them on-device. New accounts start with 500 free credits.