Open the editor with URL parameters
Use URL parameters to open an unsaved editor with a pattern and sample text. Opening the link does not save a workspace.
- Free
- Included
- Pro
- Included
- Self-hosted
- Included
For a saved, versioned link, use Save and share.
Supported parameters
| Parameter | Meaning |
|---|---|
regex | Pattern text without enclosing delimiters. |
testString | One test string, including encoded line breaks. |
flavor | Engine identifier, such as pcre2 or javascript. |
flags | Active flags; use an empty string for no flags. |
delimiter | A delimiter supported by the selected flavor. |
subst or substitution | Substitution text. |
extraction | Extraction template. |
lang | Interface language code, such as en, de, or pt-BR. |
When both substitution aliases are present, subst wins.
Specify the flavor, flags, and delimiter when the example depends on them. Omitted values can use defaults or the reader's configuration.
If you supply a flavor without flags or delimiter, the editor uses that flavor's defaults. Unsupported configuration values are normalized by the editor.
See Engines for engine identifiers and differences.
Interface language
Use lang to select the interface language when the page loads. For example, https://regex101.com/?lang=de opens the interface in German.
| Code | Language | Code | Language |
|---|---|---|---|
en | English | nl | Dutch |
fr | French | de | German |
zh | Chinese | sv | Swedish |
es | Spanish | pt | Brazilian Portuguese |
pl | Polish | ru | Russian |
ro | Romanian | it | Italian |
id | Indonesian | ja | Japanese |
ko | Korean | tr | Turkish |
vi | Vietnamese |
Codes are case-insensitive. A hyphenated locale uses its first part, so sv-SE selects Swedish and pt-BR selects Brazilian Portuguese.
Use hyphens for locale variants. An underscore form such as pt_BR is not recognized.
A supported lang value overrides the saved interface language for that page load. It does not change the saved setting.
An empty or unsupported value uses the saved language. Use lang=en to open English regardless of the saved language.
lang also works on saved workspace links. It changes interface text, not the regex flavor or the code generator's programming language.
Set flavor to choose the regex engine. In Code Generator, use Language to choose the programming language.
The code generator initially uses its configured default language. If no default is set, it selects a language from the regex flavor and editor mode.
Build a link safely
Use URLSearchParams to encode the values. It preserves spaces, Unicode, ampersands, plus signs, hash signs, and line breaks through URL encoding.
The following example opens the substitution editor:
const url = new URL('https://regex101.com/substitution')
url.search = new URLSearchParams({
regex: '(?<key>[A-Z]+)=(?<value>.+)',
testString: 'NOTE=café & tea + cake #1\nORDER=ORD-2048',
flavor: 'pcre2',
flags: 'gm',
delimiter: '/',
subst: '$1: $2',
lang: 'en',
}).toString()
console.log(url.href)
Open the printed URL in your browser. The pattern matches each line and captures its key and value.
The substitution output is:
NOTE: café & tea + cake #1
ORDER: ORD-2048
A manually concatenated + can decode as a space. A raw # starts a fragment, and a raw & separates parameters.
Encode values before sharing the link. Do not encode the complete URL as one parameter.
Editor modes
Choose the editor mode with its path:
| Path | Mode |
|---|---|
/ | Match |
/substitution | Substitution |
/extraction | Extraction |
/unit-tests | Unit tests |
/substitution-pipeline | Substitution pipeline, subject to feature access |
The mode path does not provide a schema for importing unit tests or pipeline stages through query parameters.
Saved links and privacy
Parameters seed unsaved editor routes. A saved /r/{fragment}/{version} link loads its saved workspace; query parameters do not override its pattern or test strings.
URL content can appear in browser history, copied messages, and service logs. Use synthetic examples and omit credentials or private data.
For large samples or stable revisions, save a workspace and share its versioned link.