HammerAI Review (2026): Local Models, Cloud Plans and What Private Really Covers

Local vs cloud: what the HammerAI privacy claim actually covers

HammerAI’s privacy claim is true for local models in the desktop app and does not apply to anything else, and the app is honest about that if you read past the homepage. The FAQ answers “Is my chat private?” with “It depends on which models you use,” then draws the line: on the desktop app with local models, conversations are “100% private and never leave your device”; with cloud models, messages “are sent to our servers but are not stored or used for training.” That is the clearest version of the split I have seen from any company in this category, and it deserves credit before I pick at the edges.

Local mode on HammerAI: what stays on the machine

In local mode, everything: the model file, the character JSON, the chat log and the lorebook all live on your drive, and the docs say where (the app’s data folder under AppData on Windows). The installation doc explains that HammerAI starts a local server on a random port to talk to Ollama and that the first-launch network prompt only needs internal access, not the public internet. The desktop page adds that messages are “deleted each time you close it” unless you save the chat. I tested the only part of this a user can test, by cutting the connection and continuing a conversation, and the app did not care. The overview docs put the philosophy bluntly: “There is no login - that’s how serious we are about your privacy.” Two caveats. The desktop app does check for updates and will download them automatically, so it is not a sealed box. And the code is closed, distributed through a releases-only GitHub repository, so “nothing leaves” is a documented and observed behaviour, not an audited one. Our privacy scorecard marks HammerAI at the top of the category on this basis, with the closed-source note attached.

Cloud mode on HammerAI: what the policy says and what it lists

In cloud mode HammerAI is a web service run from Vercel, Supabase and Cloudflare, and its privacy policy (last updated March 29, 2026) reads like one. The good clause first: “We do not collect any information about your conversations with characters.” The policy then lists what it does collect, which is character content you create, usage analytics through a self-hosted Umami instance, payment information through Gank, feedback with IP addresses, error data through Sentry, and anonymous crisis-referral events. It names Adsterra and Growl as advertising partners, which matters because the pricing page promises no ads on every plan including Free, so I assume those networks cover the marketing pages rather than the chat. The clause I would underline is the one about AI providers: OpenRouter is named as a provider, and the policy says messages sent to third-party AI providers may be stored by those providers according to their policies. In other words, the “not stored” promise is HammerAI’s promise about HammerAI’s servers; whether the upstream model host keeps anything is between you and OpenRouter. The App Store label lists contact info, user content, identifiers, usage data and diagnostics as data linked to you, which is what you would expect from a logged-in cloud app and is a long way from “nothing leaves your computer.” Deleting an account erases profile, private characters and private stories from the server; public content stays, unattached to you, and local chats are untouched.

The account question on HammerAI

You do not need an account for local chat, and I never made one in week one. Since version 1.0.0 in March 2026 there is a login and cloud storage for characters and chats, which is what the mobile app and the cross-device experience are built on. The trade is straightforward: sign in and your characters follow you to your phone; stay signed out and they stay in one folder on one machine. It does not push the account the way every other app in this category does, and the sign-in button sits quietly in the corner. That restraint is the most trustworthy thing about it.

HammerAI hardware requirements and model choice

HammerAI needs a dedicated GPU with 8 GB or more of VRAM for a comfortable 7B or 8B model at Q4, and the numbers get steep from there; the app’s no-configuration promise is about setup, not speed. The homepage and desktop page do not state a minimum spec, which I think is a mistake, because the hardware question is the one that decides whether HammerAI is wonderful or unusable.

What the HammerAI docs say you need

The quantizations doc is where the honest figures live. At Q4, a 3B model is a 2 to 6 GB file wanting roughly 6 to 10 GB of memory; a 7B is 4 to 8 GB on disk and about 6 to 10 GB of VRAM; a 13B is 10 to 12 GB on disk and 12 to 14 GB of VRAM; a 30B is 24 to 30 GB on disk and 26 to 36 GB of VRAM, which rules out every consumer card. Q8 roughly doubles each of those. The itch.io listing summarises it as 13B-plus models wanting 9 GB or more of VRAM, which is the optimistic end. The Ollama doc adds that the app will split a model across GPU and CPU when VRAM runs short, which works and is slow, and that an SSD matters because page-filing on a hard drive makes it slower still. The Linux doc says what happens when you get it wrong: “slow responses or responses that stutter” mean the model needs more than you have. Ollama handles Nvidia, AMD, Intel and Apple GPUs, with AMD’s 9000-series restricted to Windows and specific Ubuntu and RHEL releases. On Apple Silicon, unified memory counts, which is why a 16 GB MacBook runs a 12B where a 16 GB Windows laptop with integrated graphics crawls.

Picking a model on HammerAI

Pick the largest model that fits in your VRAM at q4_K_M, then test whether the next size up is tolerable; that is the docs’ advice and it matched my week. HammerAI’s account on ollama.com is the practical model list: the most-pulled entries are a 12B Mag-Mell merge, MythoMax 13B, Smart Lemon Cookie 7B, a 24B Omega Darker, Llama-3 Lexi Uncensored 8B and Midnight Miqu 70B, and the collection runs from 7B to 123B. Names like “Uncensored” and “After Dark” tell you what the community pulls them for; the content guidelines apply to what you publish, not to what a local model will say. Independent tests this year name Mistral-Nemo 12B as the free cloud model and put a paid model called Aion 2.0 above it, with the expected trade of better prose for slower replies. If none of that suits, the proxy setting accepts a URL, model name, context length and API key for LM Studio, OpenRouter, Featherless or any compatible endpoint, which turns HammerAI into a front end for whatever you already pay for. For the wider uncensored field, our best uncensored AI list compares hosted and local options side by side.

The HammerAI web version and WebGPU

The web app at hammerai.com has two modes: cloud, which is the default and works on anything, and local, which runs a model inside a WebGPU-capable browser through WebLLM and MLC LLM, in Chrome, Edge or Opera. The itch.io page for the web version makes the same privacy promise as the desktop app for that mode: conversations “will not leave your computer,” and the chat is kept only while the tab is open unless you save it. In practice the browser route is a demo of the idea rather than the way to use it: the model download happens every session unless the browser caches it, the choice of models is smaller, and the desktop app is faster on the same machine. Treat local-web as the way to try the app before installing, and the desktop app as the product.

HammerAI characters, lorebooks and stories

HammerAI’s character system is the SillyTavern model with a friendlier face: a card with a personality, scenario, first message and example dialogues, a lorebook that injects facts on keywords, a persona that describes you, and a library at hammerai.com/characters where the community publishes theirs. The library sorts by most liked with a Featured filter and more than fifty tags covering gender, species, profession and fandom; I could not find a character count anywhere on the site, and the App Store copy’s “thousands” is the only official figure.

Building a character on HammerAI

The creation form takes a name (used as the {{char}} placeholder), an optional display name, a personality written as tags, bullets or prose, a scenario, a first message, example dialogues in the #{{char}}: and #{{user}}: format, an avatar and background, a one-line introduction, tags, a creator’s note that the model never sees, and an SFW or NSFW content rating. Each character also carries its own system prompt and sampler settings, which is where HammerAI pulls ahead of Joyland or Character.AI: a character that needs a low temperature to stay in voice can have one without changing anything else. Save locally and the character is private and yours; upload and it enters moderation, which the docs say takes “hours to one week,” with tags required for approval and the content guidelines applied. Public avatars must be PG-13 with no nudity even on Mature characters, all characters must be 18 or older with what the guidelines call no exceptions and no loopholes, and photorealistic real people are banned. Author Mode ties uploads to an Author ID and secret so creators can appear on the leaderboard and update their cards. The desktop app imports V1 and V2 cards, so a collection from Chub AI or a SillyTavern folder works, and I moved a handful across without editing them. Every hands-on test I have read, and mine, agree that character consistency is a strength: a well-written card on a 12B model holds voice for a long session, which is the thing I marked Joyland up for and is doubly impressive here given the model is running on a desk.

How HammerAI lorebooks actually trigger

A lorebook entry is a set of comma-separated keys and a value; when a key appears in the last four messages (two of yours, two of the character’s), the value is injected into the prompt once. The doc spells out the rules: matching is case-insensitive, partial matches count (so “fire” fires on “firefighter”), duplicate hits inject once, and lorebook values do not trigger other lorebook entries. The advice is to keep values to one or two sentences and keys specific, because a vague key on a long lorebook will flood the context. HammerAI’s blog pairs it with the card sensibly: “Character cards define who the AI is. Lorebooks define what the AI knows.” The panel lives inside the chat, entries can be edited over time, and community templates circulate on Discord. What the lorebook is not is a memory: it remembers what you wrote into it, not what happened. Combined with the 8K free cloud context, that makes long storylines a maintenance job, which is why memory scores a 6 here despite the tooling being better than most.

Stories, personas, images and voice on HammerAI

Stories is a separate mode with a style and synopsis field where you alternate between writing yourself, prompting the next beat, and highlighting a passage for the model to rewrite; drafts save locally and can be published to the community story page with a title, category and tags. Personas are short profiles (the docs recommend 200 to 500 characters) covering appearance, traits and standing orders, ticked active from a list. Image generation runs in the cloud from a standalone page or an Image button in chat, with prompt, seed and three aspect ratios, and costs 10 credits per image; the paid plans list 22 image models, and the docs point to guides for running ComfyUI or WebUI Forge locally if you would rather keep images on your own card too. Text-to-speech is 5 credits per clip from a library the pricing page puts at 746 voices in 34 languages, and the App Store copy says over 300, which is the kind of inconsistency this site produces regularly. Group chats take up to ten characters, and they are chaotic in the way group chats always are. None of these extras is why you would choose the app, but all of them exist, and the free plan’s zero credits mean images and voice are strictly a paid feature.

HammerAI community and support

HammerAI’s community is a Discord server of about 5,000 members, a subreddit at r/HammerAI, and an itch.io comments page that doubles as a public bug tracker; support is the same Discord plus an email address. The public invite showed roughly 5,010 members and just under 600 online when I checked, which is a third the size of Joyland’s server and busy for a project with no marketing budget. The docs list a Creators Corner channel for promoting characters, a public roadmap channel where the community can see planned features, and a plain statement that many features are prioritised “based on people asking for things they’d like.” I could not load the subreddit, so I will not quote its size.

The itch.io comments are the honest record. Three years of them run from “when are we going to get a windows release?” through crash reports, VRAM complaints, requests for saved chats and images, and pushback when the subscription first appeared in early 2024 (“probably wouldn’t have bothered downloading it if i knew you had to subscribe for 9 bucks a month”), which is worth reading alongside the fact that local chat has stayed free the whole time. The developer answers most threads, points people to Discord, confirms the app is uncensored when asked, and explains the money plainly: “I use all the money I make to pay other devs to help work on the project.” That is the support model. There is no ticket system, no live chat, and the two contact addresses on the site ([email protected] in the policy, a Gmail address in the docs) tell you how small the operation is. Terms-wise, purchases are final, App Store subscriptions cancel through the device, and disputes go to arbitration under Delaware law. If a company with a support desk matters more to you than a model on your own drive, the wider field is in our best Character AI alternatives list, and the platforms built for explicit chat first are ranked in our best NSFW AI chat apps guide.