How to Run Technical Reference Checks That Actually Tell You Something

Reference checks occupy a strange place in most hiring processes. They are treated as a mandatory step, but almost no one treats them as a genuine information-gathering exercise. The candidate picks three people who like them. Those people say positive things. You file the notes and extend the offer.

Done this way, references are ceremony. They do not add signal and they do not protect you from a bad hire. Most candidates who turned out to be wrong hires had glowing references.

The problem is not the format. It is that most reference calls are designed to confirm a decision already made, not to surface discomfort about one.

Done properly, reference checks are among the more useful things you do at the end of a hire. Not because they will reveal dramatic red flags, but because the texture of a reference call — the pauses, the specific examples, the things a reference does not say — can confirm your confidence or prompt you to probe something you noticed in the interviews.

Who to ask for, and who to push back on

The candidate will submit a list. Before you call anyone on it, look at the list itself.

Ask for two managers and one peer, not three peers. Candidates sometimes submit three colleague references because they have not thought about it or because their managers from relevant jobs are harder to reach. Push back: you need someone who managed the candidate, assigned them work, and observed how they responded to difficult situations. A peer can describe technical ability. A manager can tell you about reliability, communication under pressure, and how the candidate handles disagreement.

Check how recent the relationships are. A reference from a job the candidate left five years ago tells you who they were then, not who they are now. For a senior hire, the last 3-4 years matter most. If the most relevant manager reference is from 2020 and the candidate left that job in 2021, ask if there is anyone more recent.

Ask which role the reference corresponded to. A reference who worked with the candidate as a junior developer is less useful for validating a senior hire than someone who observed them leading technical work. If the candidate’s most relevant recent work was at a company where they are not offering references — they are still there, the relationship ended badly, or it was a short stint — note it and factor it in.

The call structure

A reference call runs about 20-25 minutes. Prepare specific questions, but do not read them robotically. The goal is a conversation where the reference feels comfortable being honest.

Opening. Establish the relationship. “How long did you work with [candidate], in what capacity, and what kind of work were they doing?”

This confirms what you already know (or reveals a mismatch: a “manager” who was actually a team lead with no authority to assign work).

Technical work. “Can you describe a project [candidate] led or made a significant contribution to while you worked together? What did they deliver, and how did they approach technical decisions?”

You are looking for a specific example. Generic praise (“they’re excellent at problem-solving”) without an example usually means the reference knows the candidate personally but has limited technical visibility into their work. Specific examples — “she rebuilt our authentication system when we moved to OAuth and the documentation she left made the next team’s life much easier” — are what you want.

How they handle difficulty. “Tell me about a time when something went wrong on a project [candidate] was involved in. How did they respond?”

If the reference says it never went wrong, that is unlikely and tells you they are being careful. If they give a real answer, probe further: what did the candidate do specifically, and what would they have done differently?

The inversion question. “What is something [candidate] would need to develop or work on to reach the next level in their career?”

This is the single most important question on the call. The reference has to say something negative or developmental about someone they presumably like and respect. Watch for three things:

• A pause before answering (they are searching for something real, which suggests there is something real)
• A developmental answer that sounds like a genuine observation (“she could be more assertive in meetings when she disagrees with a direction”)
• Deflection back to positives without engaging with the question (“honestly I cannot think of anything, she was excellent”)

The third response is sometimes genuine. It is more often a reference who does not want to say anything that could hurt the candidate’s chances. Follow up: “If you were hiring her into a role that had some complexity around X [something you noticed in interviews], is there anything you would want to know going in?”

Closing. “Would you hire this person again if the opportunity were right?”

This is a direct yes/no with an easy out (“if the opportunity were right”). Hesitation, qualifications, or “I’d have to think about what the role was” are informative. An immediate “absolutely, in a heartbeat” is the baseline you expect from a reference who agreed to the call.

What the pauses tell you

Reference calls carry tone. A reference who is genuinely enthusiastic talks faster, interrupts themselves to add details, and offers examples without prompting. A reference who is being careful about what they say tends to answer precisely, pause before answering the inversion question, and give answers that sound slightly structured.

Neither pattern is disqualifying on its own. But a reference call where the tone shifts significantly between the technical questions (where the reference is at ease) and the inversion question (where they slow down) is telling you something. The reference knows something they are choosing not to say directly.

You can often prompt it with a softer framing: “I want to make sure [candidate] is set up for success in this role. Is there anything about the environment or team dynamics that would help them thrive, or that they would find difficult?”

This gives the reference an opening to share concerns framed as support rather than criticism. It is easier for someone to say “she does better with clear direction than open-ended briefs” than “she struggled when the requirements were ambiguous.” The substance is similar.

Legal considerations

In the US, former employers can say essentially anything true about a former employee. In practice, many HR departments instruct managers to confirm only dates of employment and job title to avoid defamation claims. This means a manager who wants to tell you something negative may not be able to do it through official channels.

Some managers will tell you informally what they cannot say officially. Listen carefully to the tone of a call where a manager says “I can only confirm employment dates, per company policy” — whether they volunteer that limitation immediately or only after you have asked several questions tells you something.

In the UK and EU, data protection rules (GDPR) impose additional constraints. References are permitted but the employer must not process personal data beyond what is necessary. Asking for a character reference versus a factual employment confirmation is a distinction that matters in regulated environments.

When in doubt, consult your legal counsel on what you can ask and how to document the call.

How reference checks fit the broader process

References are one part of a layered hiring process. They work best when combined with a rigorous technical screen, a structured interview, and a take-home task that shows you real work.

If you are unsure about a candidate after the interview process, reference checks may surface what is making you uncertain. If you are confident, they are a light confirmation step. They are not a substitute for a thorough technical screen — a glowing reference cannot tell you whether someone can write idiomatic Go or model a domain correctly in TypeScript.

The full process is covered in the technical interview guide. For per-role screening, see the guides on hiring a full-stack developer, a TypeScript developer, or a vetted software developer — each has take-home tasks and interview questions that give you concrete material before you get to the reference stage.