Fiddler AI vs LangSmith: who uses which
Customers, public proof and the companies that use both.
On usedby, 10 companies use Fiddler AI and 43 use LangSmith. No company is listed with both yet. LangSmith leads among the Fintech & Payments companies on usedby that use either tool.Latest check Oct 6, 2026: 47 of 53 public lines checked. Counts include every proof level, job-post signals included. Companies named on both have a confirmed or observed line on each side.
Who uses Fiddler AI, LangSmith, or both
Every company with a public proof for at least one of the two tools.
10
use only Fiddler AI
0
companies use both
43
use only LangSmith
10 companies use only Fiddler AI, 43 use only LangSmith and 0 use both, out of the 53 companies on usedby that use at least one of them.
Where it lands
Newest customers
No new customer since tracking started on October 6, 2026.
Where it lands
Newest customers
No new customer since tracking started on October 3, 2026.
Who uses both
Companies with a confirmed or observed line on both tools.
By industry
Which tool the companies on usedby use, by industry. Shares of the companies on usedby that use Fiddler AI, LangSmith or both: a share of the companies on usedby, not of the market.
Fiddler AI onlyBothLangSmith only
More common with LangSmith
- Fintech & Payments4 of the 6 Fintech & Payments companies on usedby that use either tool use LangSmith.
- HR & Recruiting5 of the 5 HR & Recruiting companies on usedby that use either tool use LangSmith.
Source: confirmed and observed usedby lines. Job-post signals, the weakest proof level, are left out of these shares.
Side by side
Facts from our data and from each vendor's public pages. Each line says where it comes from.
Fiddler AILangSmithWhat customers report
Results as the vendor or the customer published them, with the source and the date.
Questions about Fiddler AI and LangSmith
Which is used more, Fiddler AI or LangSmith?
LangSmith has more customers on usedby: 43 against 10 for Fiddler AI.
Do companies use both Fiddler AI and LangSmith?
usedby has not found a company with a confirmed or observed line on both Fiddler AI and LangSmith yet.
Who uses Fiddler AI?
10 companies on usedby, each with the public page that shows it. See who uses Fiddler AI.
Who uses LangSmith?
43 companies on usedby, each with the public page that shows it. See who uses LangSmith.
How does usedby count customers?
A company counts when a public page shows it: a vendor's customer page, a case study, a press release or a job post, most saved with a dated capture. Every line is a customer, at one of three proof levels: confirmed, observed or signal (a job post, the weakest). A company is named as using both tools when its lines on both are confirmed or observed.