Sentence case converter
“hello world. this is a TEST.” becomes “Hello world. This is a test.”: 2 sentences, each starting with a capital, everything else in lowercase. Fix shouted reviews, title-case drafts and canned replies in one pass. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Text
- hello world. this is a TEST.
- Result
- Hello world. This is a test.
- Text
- Hello world. This is a test.
- Original
- hello world. this is a TEST.
- Length
- 28
Sentence case is the everyday style of ordinary prose: the first letter of each sentence is capital, and everything else is lowercase unless house style later re-adds proper names. Writers, editors, support teams, and product UIs constantly receive ALL CAPS pastes, title-case headlines, and mixed case drafts that need a single deterministic pass before publishing. Empty or whitespace-only strings fail with invalid input so pipelines never store blank titles.
What sentence case means and how sentences are detected
Sentence case is not title case and not shouting. Title case capitalizes most words; shouting leaves every letter upper; sentence case resets the stream so only sentence heads rise. This converter first lowercases the entire string so residual capitals disappear, then walks the characters once.
The first alphabetic character of the whole text is uppercased. After each ASCII period, exclamation mark, or question mark, the next alphabetic character is uppercased again, even if spaces, tabs, or newlines sit between the terminator and that letter. Digits, symbols, and whitespace keep their positions; only letters change case.
Multi-sentence paragraphs such as hello world. how are you? become Hello world. How are you?
in one pass. Text without a trailing terminator still counts as one sentence when it contains letters. Inputs that are only digits or punctuation produce a lowercased result with sentence count one, because there is content but no alphabetic head to raise a second time.
Abbreviations like Dr. Name will re-capitalize after the period—that is the honest limit of a pure terminator rule without a dictionary of titles.
What you can do with it
Support macros and ticket templates
Support tools normalize agent replies and canned responses so customer-facing text follows a consistent sentence-case house style.
UGC feeds and review moderation
Product review pipelines rewrite mixed or shouted user text into readable sentence case before display, with empty submissions rejected early.
FAQ
How do I convert text to sentence case?
The response result field is the sentence-cased output; original echoes your input for comparison.
Does this preserve acronyms and proper names?
No. The algorithm lowercases every letter first, then capitalizes only sentence heads. Mid-sentence capitals are intentionally reset.
Is the sentence case converter free?
The browser tool runs free on your device.
How are sentence boundaries detected?
After each ASCII period, exclamation mark, or question mark, the next alphabetic character is uppercased. The first letter of the whole string is also uppercased.
Why is the word after Dr. capitalized?
Because every period counts as the end of a sentence; there is no dictionary of abbreviations. After Dr. or etc. the next word starts with a capital, so check those spots once the text is converted.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/str/sentence-case \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"text":"hello world. this is a TEST."}'const res = await fetch("https://api.kit.forhosting.com/str/sentence-case", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"text": "hello world. this is a TEST."
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/str/sentence-case",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"text": "hello world. this is a TEST."
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/str/sentence-case", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"text":"hello world. this is a TEST."}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"text":"hello world. this is a TEST."}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/str/sentence-case", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"text": "hello world. this is a TEST."
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "str.sentence_case",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
What sentence case means and how sentences are detected
Prefer this tool when the search intent is literally convert to sentence case, sentence case converter, or fix casing of sentences; use separate tools for camelCase, snake_case, or URL slugs. The algorithm is fully deterministic: identical inputs always yield identical JSON with no network, no random seed, and no wall clock.
Input contract, empty rejection, and reading the response
Source text follows the same retention rules as other KIT parse items. Send a JSON body with the required string field text set to the non-empty message you want rewritten. Aliases input, value, s, and content are accepted when older forms or client generators use those names. Missing text, a non-string value, an empty string, or a string that is only whitespace all raise invalid_input with a message that names the problem, and those failures are not charged on the prepaid API. Use result alone when you only need the cleaned paragraph; use original and result together when a review UI must show before-and-after; use sentence_count when a linter or style checker estimates how many sentence starts were adjusted. Keep payloads to ordinary document sizes suitable for a Worker isolate rather than multi-megabyte dumps; this product is a prose formatter, not a bulk file processor.
API usage, pricing, editorial workflows, and practical limits
Call the free in-browser sentence case converter for editorial cleanup, support macros, classroom demos, and one-off pastes without installing a desktop utility or writing a one-liner in every language. Another workflow normalizes user-generated reviews so a feed does not alternate between shouting and whisper-case mid-page. Do not expect mid-sentence proper nouns to survive: names and brand acronyms are lowercased by design and must be re-styled by a later editorial pass if house style requires them. Authors shipping SDKs can document text as the only required field and show a multi-sentence example plus an empty-string error example so integrators see both sides of the contract. Use the prepaid KIT API when a CMS worker, ticket system, localization pipeline, or mobile backend needs the same transform under balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. A typical workflow lowercases a product description pasted in all caps, runs this endpoint, then stores result as the display body while logging original for audit. Pair this endpoint with a URL slug generator when a headline must also become a route, but keep the steps separate so each landing page matches a single search intent—sentence case for human prose, slug tools for paths.
Integration use cases
Editorial and CMS cleanup
Editors paste ALL CAPS or title-case drafts into a CMS field; the endpoint returns sentence case ready to publish without hand-editing every paragraph.
Technical questions
What happens if text is empty?
Empty strings and whitespace-only strings fail with invalid_input and are not charged. Provide at least one non-whitespace character.