Free tool
Instagram caption generator
Upload your post image and Gemini will analyze what is in the frame, then write three on-brand caption variations. Or describe the post in text. Either way, three seconds, no login, no credit card.
How it works
- Upload the image you are about to post (JPG, PNG, or WebP up to 4MB). Gemini analyzes it and references actual visual details in the captions: a steam wisp, the brick wall, the morning light, the specific product in the frame. Or skip this step and describe the post in text.
- Add a sentence of context. Anything the image does not show: the launch date, the price, the new flavor, the special occasion. With an image attached this field is optional, but a single sentence sharpens every caption.
- Set the vibe and the brand voice. Five vibes cover most small businesses; the brand voice field lets you pin three adjectives the captions should sound like.
- Pick a hashtag policy. None, three to five, or eight to twelve. The model picks niche-relevant tags rather than spam tags.
- Generate three variations. Short (one-line hook), medium (two to three sentences), long (with the call-to-action woven in). Tab through them, copy the one you want, paste into Instagram.
What this tool does not do (yet)
This standalone version writes captions. It does not generate the matching on-brand image, batch-generate a week of posts, maintain a structured brand profile across every post, or wire up the scheduling step. The full Sevenposts product does all of that in one workflow.
If you want all of it, join the Sevenposts waitlist. Or read the longer write-up: the eight things an AI tool for social media content creation actually needs to do.
Frequently asked questions
Is this Instagram caption generator really free?+
Yes. You get 2 free generations per day with no signup. Drop your email and that bumps to 5 per day. We do not ask for a credit card. We do not run ads on the page.
Can I upload my post image and get a caption that matches it?+
Yes. Drop in a JPG, PNG, or WebP up to 4MB and Gemini analyzes the image (subject, mood, props, colors, light) and writes captions that reflect what is actually in the frame. You can also add an optional sentence of context the image does not show, like a launch date or a price.
Which AI model writes the captions?+
We use Google Gemini 2.5 Flash. It is fast (under 3 seconds per generation), cheap to run, and multimodal (so it sees uploaded images as part of the same call as the text prompt). It produces captions that read like a thoughtful small-business owner wrote them, not like a bot.
How is this different from ChatGPT?+
ChatGPT works fine if you write a 200-line prompt every time and remember to upload the image. This tool ships the prompt for you. The form already encodes the brand voice direction, the hashtag policy, the length variations, the image-analysis instructions, and the rules against AI-speak openers like "Looking for..." or "Ready to...". You fill a few fields, optionally drop an image, and get three captions.
Can the tool write captions in my brand voice?+
Yes. The brand voice field accepts three adjectives (e.g. "unhurried, restrained, confident"), and the vibe selector picks the overall register (friendly, witty, professional, minimal, playful). The full Sevenposts product (in waitlist now) takes a structured brand profile that produces fully consistent output across every post in a feed.
Will the captions sound generic?+
They will not start with "Looking for..." or "Ready to..." or any of the other AI-speak patterns. The system prompt explicitly bans them. Specificity comes from the input you give it. Uploading the actual image you are about to post is the single biggest specificity boost: the captions stop guessing and start describing.
Does this generate the image too?+
Not yet. This standalone tool only writes captions and analyzes images you already have. The full Sevenposts product (sign up for the waitlist on the home page) generates the matching on-brand image, the caption, and the hashtag set in one pass, batched across a whole week of posts.
What happens to the image I upload?+
It is sent to Google Gemini once for the caption generation, then discarded. We do not store it on our servers. The base64 payload sits in your browser memory until you reload or remove it.
How do I use the captions?+
Pick the variation that fits the post (short for hooks, medium for most posts, long when the call-to-action matters), copy it, paste it into Instagram. The hashtags are pre-formatted to drop on a new line.