Convert to lowercase
Turn any text into lower case in one step: Hello World becomes hello world, and you see that 2 letters changed. Accents such as É and Ñ become é and ñ instead of disappearing. 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
- Result
- hello world
- Length
- 11
- Original length
- 11
- Changed count
- 2
Converting text to lowercase is one of the most common string hygiene steps in forms, search indexes, identifiers, and data pipelines. This tool takes the text you enter, folds every letter to its lower-case Unicode equivalent, and returns the lowercased string together with length and change metadata so you can see whether anything actually differed. Digits, punctuation, emoji, and whitespace stay as they are; only alphabetic case is adjusted.
How lowercase conversion works
Lowercasing maps each character that has an upper-case or title-case form to its lower-case counterpart according to the Unicode case mapping tables implemented by the JavaScript host. For basic Latin this is the familiar A–Z to a–z fold. For accented European letters such as É, Ñ, and Ü the mapping produces é, ñ, and ü without stripping diacritics.
Greek, Cyrillic, and many other scripts follow the same rule set so multi-language datasets normalize consistently. Empty strings fail validation before any transform runs. Because the path is pure parse arithmetic over strings, latency stays sub-millisecond for typical form sizes and the published cost model is analytic rather than model-token based.
Where lowercase tools show up in real work
Product and growth teams normalize email local-parts, coupon codes, and username candidates to lower case before uniqueness checks so User@Example.com and user@example.com do not create duplicate accounts. Search and tagging systems fold query strings and facet labels so filters match regardless of how editors capitalized a tag. Data engineers cleaning exports from CRM tools, spreadsheets, and legacy databases often force free-text columns to lower case before joining on soft keys.
Content moderators and support agents paste messy ticket titles into a lower-case box before filing them into keyword rules that assume a single case. If you later need uppercase conversion, title case, slugify, accent stripping, or language-aware case folding with an explicit locale, treat those as separate search intents and landings rather than overloading this convert-to-lowercase page.
What you can do with it
Normalize emails and usernames
Fold registration and login fields to lowercase before uniqueness checks so mixed-case duplicates cannot slip through.
Search and filter consistency
Normalize query strings and facet labels so filters match regardless of how editors capitalized source text.
FAQ
What does convert to lowercase do?
It maps every letter in your text to its Unicode lower-case form and returns the lowercased string plus length and change metadata. Digits and punctuation are left unchanged.
What happens if I send empty text?
Empty strings are rejected so clients notice missing fields instead of receiving a silent empty result.
Does it handle accented and non-Latin letters?
Yes. Conversion uses Unicode-aware toLowerCase, so characters such as É, Ñ, and many Greek or Cyrillic capitals fold correctly without stripping diacritics.
What does it cost?
The browser tool is free and runs locally.
How can I tell whether my text was already in lower case?
Look at the count of changed characters. If it is zero, the result is identical to what you typed, which is a quick way to check emails or tags before saving them.
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/lowercase \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"text":"Hello World"}'const res = await fetch("https://api.kit.forhosting.com/str/lowercase", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"text": "Hello World"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/str/lowercase",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"text": "Hello World"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/str/lowercase", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"text":"Hello World"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"text":"Hello World"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/str/lowercase", 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"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "str.lowercase",
"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
Empty input is rejected with a clear validation error instead of silently returning an empty payload, which protects clients that forgot to bind a field. No network round-trips inside the engine, no random seeds, and no clock dependence—identical text always produces identical JSON.
How lowercase conversion works
A few Unicode edge cases can change string length under case conversion in theory; this engine reports both original_length and length so callers can detect that situation. The algorithm walks the full string once, builds the lowercased result, then compares character positions to compute changed and changed_count. Extremely long payloads above the documented character cap also fail with invalid_input so a single request cannot monopolize Worker memory.
What you send and what you get back
Send a single required field named text containing the non-empty string you want lowercased. Numbers and booleans are coerced to their decimal or true/false text forms; objects, arrays, NaN, and Infinity are rejected. Aliases such as input, value, data, s, message, string, content, and body are accepted for convenience when wiring older clients. On success the response echoes the original text, the lowercased result, the result length, the original length, a boolean changed flag, a changed_count of differing positions, and operation set to lowercase. When the input was already entirely lower case, result equals text, changed is false, and changed_count is zero—useful as a no-op detector in ETL guards. Classic checks include Hello World becoming hello world, mixed identifiers like User_ID-42 becoming user_id-42, and strings with accents such as CAFÉ becoming café. Wire the free browser form for quick paste-and-copy work, then call the identical contract from scripts when you normalize bulk CSV columns or API payloads. Pricing for successful API calls is the published base of $0.002 per item; validation failures including empty text do not consume prepaid balance.
Where lowercase tools show up in real work
Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Clean CSV and API free-text columns
Lowercase tags, SKUs, and soft-join keys in bulk pipelines with the same result shape as the browser tool.
Technical questions
Will already-lowercase text change?
No. If every character is already lower case, result equals the original text, changed is false, and changed_count is zero.