Loading page
About this tool
Build mongodb:// and mongodb+srv:// URIs with replica set, auth source, read preference, write concern and TLS options.
The MongoDB Connection String Builder assembles a MongoDB connection URI in the official Connection String format — mongodb://user:password@host1:27017,host2:27017/db?options or the DNS seed list form mongodb+srv://cluster.example.mongodb.net/db — with credentials percent-encoded as the spec requires. It covers replicaSet, authSource, readPreference, write concern (w), tls, retryWrites, maxPoolSize and appName, and enforces the +srv rules: one host, no port. Everything is generated locally in the browser.
Open MongoDB Connection String Builder on AltFTool — it loads instantly in your browser.
Enter Hosts (comma separated host:port) or tick 'Use mongodb+srv://' for an Atlas-style DNS seed list — one host, no port — then add the optional User, Password and default auth database.
Set replicaSet, authSource, Read preference, Write concern (w), TLS, maxPoolSize and appName; the URI rebuilds live with credentials percent-encoded per the connection string spec.
Review the option-by-option list under the Connection URI panel and press Copy URI to copy the finished string — everything is generated locally in your browser.
User names and passwords are percent-encoded exactly as the MongoDB connection string spec requires.
mongodb+srv:// is validated to a single host with no port, matching how DNS seed lists actually work.
Multiple host:port members, replicaSet, read preference and write concern handled in one form.
mongodb://user:password@host1:27017,host2:27017/defaultauthdb?replicaSet=rs0&authSource=admin — the default port is 27017, multiple replica-set members are comma-separated, and options follow as query parameters. The alternative mongodb+srv:// form names a single DNS host whose SRV records list the members.
mongodb:// lists every host explicitly, while mongodb+srv:// gives one DNS name and the driver discovers the members from SRV records — which is why +srv URIs must not include a port and take exactly one host. With +srv, TLS also defaults to enabled, which is the form MongoDB Atlas gives you.
Percent-encode them: the spec requires ':', '/', '?', '#', '[', ']', '@' and '%' in the user name or password to be percent-encoded, so p@ss/1 becomes p%40ss%2F1. Unencoded characters make the driver misparse the URI, which typically surfaces as an authentication or host-resolution error.
It tells the driver which database holds the user's credentials, independent of the database named in the URI path. Users created in the admin database need authSource=admin; if the option is omitted, the driver authenticates against the database in the path, or admin when no path database is given.